1993 World Trade Center bombing

On February 26, 1993, Ramzi Yousef and a group of associates carried out a van-bomb attack in the underground parking garage beneath the North Tower of the World Trade Center in New York City. Yousef and Eyad Ismoil drove a yellow Ford Econoline Ryder van into the garage's B-2 level around noon, and Yousef ignited a 20-foot fuse before fleeing. The bomb, an approximately 1,310–1,500-pound urea nitrate–hydrogen gas enhanced device, exploded at 12:18 p.m., opening a 100-foot-wide hole through four sublevels of concrete. Yousef's intent, according to trial transcripts, was for the North Tower to collapse into the South Tower, killing an estimated 250,000 occupants of both buildings; the towers did not collapse, but the garage was severely damaged.

The bombing killed six people: John DiGiovanni, Robert Kirkpatrick, Stephen Knapp, Bill Macko, Wilfredo Mercado, and Monica Rodríguez Smith, who was seven months pregnant. More than 1,000 people were injured, mostly during the evacuation, which was hampered by smoke filling unpressurized stairwells. About 50,000 people were evacuated, and a group of 17 kindergartners was trapped in an elevator between the 35th and 36th floors for five hours.

The plot was organized by Yousef with associates including Ahmed Ajaj, Mahmud Abouhalima, Mohammed A. Salameh, Eyad Ismoil, Nidal Ayyad, and Abdul Rahman Yasin. Investigators traced a vehicle identification number from a recovered axle fragment to a Ryder van rented by Salameh, who was arrested when he returned to collect his rental deposit. This led investigators to Yasin's Jersey City apartment, which he shared with his mother in the same building as Yousef's apartment; Yasin was briefly questioned by the FBI and released, then flew to Iraq the next day. He was later indicted but never apprehended by U.S. authorities and was placed on the FBI's Most Wanted Terrorists list in 2001.

In March 1994, Salameh, Ayyad, Abouhalima, and Ajaj were convicted on charges including conspiracy, explosive destruction of property, and interstate transportation of explosives; they were sentenced in May 1994 to 240 years in prison. In November 1997, Ramzi Yousef, described as the organizer of the bombing, and Eyad Ismoil, who drove the van, were also convicted. Diplomatic Security Service special agents, working with Pakistani intelligence, located and arrested Yousef, though the FBI received public credit for the case.

During the trials, it emerged that FBI informant Emad Salem had secretly recorded conversations with his FBI handlers, alleging FBI knowledge of bomb-building activity; federal authorities disputed his account, and the New York Times reported the tapes did not clarify how much federal authorities knew in advance. Civil litigation by victims against the Port Authority of New York and New Jersey resulted in a 2005 jury verdict assigning 68 percent liability to the Port Authority and 32 percent to the terrorists, a decision upheld on appeal in 2008 before later related rulings addressed the scope of Port Authority liability.