On February 26, 1993, Ramzi Yousef and associates carried out a van bomb terrorist attack below the North Tower of the World Trade Center in New York City. The approximately 1,500-pound (680 kg) urea nitrate–hydrogen gas enhanced device was intended to make the North Tower collapse onto the South Tower, taking down both skyscrapers and killing tens of thousands of people. While it failed to do so, it was successful in killing six people, including a pregnant mother, and caused over a thousand injuries. About 50,000 people were evacuated from the buildings that day.
The attack was planned by a group of terrorists including Yousef, Ahmed Ajaj, Mahmud Abouhalima, Mohammed A. Salameh, Eyad Ismoil, Nidal Ayyad, and Abdul Rahman Yasin. In March 1994, four men were convicted of carrying out the bombing: Ajaj, Abouhalima, Ayyad, and Salameh. The charges included conspiracy, explosive destruction of property, and interstate transportation of explosives. In November 1997, two more were convicted: Ramzi Yousef, the organizer behind the bombings, and Eyad Ismoil, who drove the van carrying the bomb.
Emad Salem, an FBI informant and a key witness in the trial of Yousef, Abdul Hakim Murad, and Wali Khan Amin Shah, stated that the bomb itself was built under supervision from the FBI. During his time as an FBI informant, Salem recorded hours of telephone conversations with his FBI handlers. In tapes made after the bombing, Salem alleged that an unnamed FBI supervisor declined to move forward on a plan that would have used a "phony powder" to fool the conspirators into believing that they were working with genuine explosives.
Planning and organization
Yousef arrived illegally in the United States on September 1, 1992, traveling with Ahmed Ajaj from Pakistan, though both sat apart on the flight and acted as though they were traveling separately. Ajaj tried to enter using a forged Swedish passport, though it had been altered and thus raised suspicions among Immigration and Naturalization Service (INS) officials at John F. Kennedy International Airport. When officials put Ajaj through secondary inspection, they discovered bomb-making instructions and other materials in his luggage, and arrested him. The name Abu Barra, an alias of Mohammed Jamal Khalifa, appeared in the manuals. Yousef entered on a false Iraqi passport claiming political asylum, and was given a hearing date.
Yousef set up residence in Jersey City, New Jersey, traveled around New York and New Jersey and called Sheikh Omar Abdel-Rahman, a controversial blind Muslim cleric, via cell phone. After being introduced to his co-conspirators by Abdel Rahman at the latter's Al-Farooq Mosque in Brooklyn, Yousef began assembling the 1,500-pound (680 kg) urea nitrate–hydrogen gas enhanced device for delivery to the WTC. He ordered chemicals from his hospital room when he had been injured in a car crash – one of three accidents caused by Salameh in late 1992 and early in 1993.
El Sayyid Nosair, one of the blind sheikh's men, was arrested in 1991 for the murder of Rabbi Meir Kahane. According to prosecutors, "the Red" Mahmud Abouhalima, also convicted in the bombing, told Wadih el Hage to buy the .357 caliber revolver used by Nosair in the Kahane shooting. In the initial court case in NYS Criminal Court, Nosair was acquitted of murder but convicted of gun charges (in a related and follow-up case in Federal Court, he was convicted). Dozens of Arabic bomb-making manuals and documents related to terrorist plots were found in Nosair's New Jersey apartment, with manuals from Army Special Warfare Center at Fort Bragg, North Carolina, secret memos linked to the Joint Chiefs of Staff, and 1,440 rounds of ammunition.
According to the transcript of his trial, Yousef hoped that his explosion would topple Tower 1 which would fall into Tower 2, killing the occupants of both buildings, which he estimated to be about 250,000 people in revenge for U.S. support for Israel against Palestine.
According to journalist Steve Coll, Yousef mailed letters to various New York newspapers just before the attack, in which he claimed he belonged to "Liberation Army, Fifth Battalion".
These letters made three demands: an end to all US aid to Israel, an end to US diplomatic relations with Israel, and a pledge by the United States to end interference "with any of the Middle East countries' interior affairs." He stated that the attack on the World Trade Center would be merely the first of such attacks if his demands were not met. Yousef did not make any religious justification for the bombing. When asked about his religious views, he was evasive.
Attack
On Friday, February 26, 1993, Ramzi Yousef and a Jordanian friend, Eyad Ismoil, drove a yellow Ford Econoline Ryder van into Lower Manhattan, and pulled into the public parking garage beneath the World Trade Center around noon. They parked on the underground B-2 level. Yousef ignited the 20-foot (6.1 m) fuse, and fled. Twelve minutes later, at 12:18 p.m., the bomb exploded in the underground garage, generating an estimated pressure of 150,000 pounds per square inch (1.0 GPa). The bomb opened a 100-foot-wide (30 m) hole through four sublevels of concrete. The detonation velocity of this bomb was about 15,000 feet per second (10,000 mph; 4.6 km/s).
The bomb instantly cut off the World Trade Center's main electrical power line, knocking out the emergency lighting system. The bomb caused smoke to rise to the 93rd floor of both towers, including through the stairwells (which were not pressurized), and smoke went up the damaged elevators in both towers. With thick smoke filling the stairwells, evacuation was difficult for building occupants and led to many smoke inhalation injuries. Hundreds were trapped in elevators in the towers when the power was cut, including a group of 17 kindergarteners on their way down from the South Tower observation deck, who were trapped between the 35th and 36th floors for five hours.
Six people were killed: five Port Authority employees, one of whom was pregnant, and a businessman whose car was in the parking garage. Additionally, over 1,000 people were injured, most during the evacuation that followed the blast. A report from the US Fire Administration states that "Among the scores of people who fled to the roofs of the towers, 28 with medical problems were airlifted by New York City police helicopters". It is known that 15 people received traumatic injuries from the blast and 20 complained of cardiac problems. One firefighter was hospitalized, while 87 others, 35 police officers, and an EMS worker were also injured in dealing with the fires and other aftermath.
Also as a result of the loss of power, most of New York City's radio and television stations (except WCBS-TV (channel 2)) lost their over-the-air broadcast signal for almost a week, with television stations only being able to broadcast via cable and satellite via a microwave hookup between the stations and three of the New York area's largest cable companies, Cablevision, Comcast, and Time Warner Cable. Telephone service for much of Lower Manhattan was also disrupted.
Yousef's plan was that the North Tower would fall onto the South Tower, collapsing them both. The tower did not collapse, but the garage was severely damaged in the explosion. Had the van been parked closer to the WTC's poured concrete foundations, Yousef's plan might have succeeded. Yousef escaped to Pakistan several hours after the bombing.
Bomb's characteristics
First reports described the explosion as "having the characteristics of from 200 to 300 pounds of a plastic explosive called Semtex". According to an article published in 1997, Semtex was only used as a detonating charge in the bomb but it is unknown how the terrorists would have obtained Semtex (which is not a "homemade" explosive, unlike other supposed components of the bomb).
According to the FBI, Yousef was assisted by Iraqi bomb maker Abdul Rahman Yasin, who helped assemble the complex 1,310-pound (590 kg) bomb, which was made of a urea nitrate main charge with aluminum, magnesium and ferric oxide particles surrounding the explosive. The charge used nitroglycerine, ammonium nitrate dynamite, smokeless powder and fuse as booster explosives. Three tanks of bottled hydrogen were also placed in a circular configuration around the main charge, to enhance the fireball and afterburn of the solid metal particles. The use of compressed gas cylinders in this type of attack closely resembles the 1983 Beirut barracks bombing 10 years earlier. Both of these attacks used compressed gas cylinders to create fuel-air and thermobaric bombs that release more energy than conventional high explosives.
According to testimony in the bomb trial, only once before the 1993 attack had the FBI recorded a bomb that used urea nitrate. Moreover, FBI agent Frederic Whitehurst was strongly critical of the procedures used to determine that the bomb contained urea nitrate; according to his testimony, he urinated in a vial, dried the urine and gave a sample of it to the analysts, who still concluded that the substance handed to them was urea nitrate. The Ryder van used in the bombing had 295 cubic feet (8.4 m3) of space, which would hold up to 2,000 pounds (910 kg) of explosives. However, the van was not filled to capacity. Yousef used four 20-foot-long (6.1 m) fuses, all covered in surgical tubing. Yasin calculated that the fuse would trigger the bomb in twelve minutes after he had used a cigarette lighter to light the fuse.
Yousef wanted the smoke to remain in the tower, smothering people inside, killing them slowly.
There was a popular belief at the time that there was cyanide in the bomb, which was reinforced by Judge Duffy's statement at sentencing, "You had sodium cyanide around, and I'm sure it was in the bomb." However, while the bomb's true composition was not able to be ascertained from the crime scene, Robert Blitzer, a senior FBI official who worked on the case, stated that there was "no forensic evidence indicating the presence of sodium cyanide at the bomb site." Furthermore, Yousef is said only to have considered adding cyanide to the bomb, and to have regretted not doing so in Peter Lance's book 1000 Years for Revenge.
Victims
Six people were killed:
- John DiGiovanni, age 45, a dental products salesperson.
- Robert "Bob" Kirkpatrick, age 61, Senior Structural Maintenance Supervisor.
- Stephen Knapp, age 47, Chief Maintenance Supervisor, Mechanical Section.
- Bill Macko, age 57, General Maintenance Supervisor, Mechanical Section.
- Wilfredo Mercado, age 37, a receiving agent for Windows on the World restaurant.
- Monica Rodríguez Smith, age 35, a secretary, who was seven months pregnant.
At the time of the bombing, Smith was checking time sheets in her office on the B-2 level; Kirkpatrick, Knapp and Macko were eating lunch together in an employees' break room next to Smith's office; Mercado was checking in deliveries for the restaurant; and DiGiovanni was parking in the underground garage.
Memorials
Memorial fountain
A granite memorial fountain honoring the victims who died during the bombing was designed by Elyn Zimmerman and dedicated on May 25, 1995, on the Austin J. Tobin Plaza, directly above the site of the explosion. It contained the names of the six adults who were killed in the attack, as well as an inscription written both in English and Spanish that read: "On February 26, 1993, a bomb set by terrorists exploded below this site. This horrible act of violence killed innocent people, injured thousands, and made victims of us all."
The fountain was destroyed with the rest of the World Trade Center during the September 11 attacks. A recovered fragment of the fountain marked "John D", from the name of John DiGiovanni, was later incorporated into a temporary memorial designed by Port Authority architect Jacqueline Hanley, and erected on the Liberty Street side of the site following the September 11 attacks. The memorial was visible across a fence barrier but was not open to the public. Today, the fountain fragment is currently located at the National September 11 Memorial & Museum. The rest of the fountain was never recovered, and any of its remains were removed from Ground Zero along with the rest of the rubble.
Post-9/11 memorials
At the 9/11 Memorial, which opened on the tenth anniversary of the 2001 attacks, the people who died in the 1993 bombing are memorialized at the North Pool, on Panel N-73. The recovered fragment of the memorial fountain is on display among other artifacts related to the bombing inside the museum's historical exhibition.
The Postcards memorial in Staten Island contains the name of Stephen Knapp, the sole person from that borough who died in the bombing.
On September 8, 2026, the Port Authority of New York and New Jersey dedicated a new memorial at Liberty Park, to honor to the four workers killed in the February 1993 bombing and the 84 who died in the 9/11 attacks. That includes 37 members of the Port Authority Police Department, which is the largest loss of life by any police force in the U.S. in a single event. The memorial also has the names of agency workers who got sick or died while working on post 9/11 recovery efforts.