Case overview
On February 26, 1993, a 1,200-pound urea nitrate bomb detonated in the underground parking garage of the World Trade Center’s North Tower, killing six people and injuring more than 1,000. The explosion carved a five-story crater through reinforced concrete and exposed a coordinated plot to destabilize one of the nation’s most recognizable landmarks. Four men were convicted in 1994, and the investigation revealed connections to broader networks targeting American interests.
The explosion and immediate aftermath
At 12:17 p.m. on a Friday afternoon, the bomb exploded in a rented yellow Ford Econoline van parked on the B-2 level of the parking garage beneath the North Tower. The blast ruptured water mains, severed electrical cables, and filled stairwells with smoke. More than 50,000 people were inside the complex.
Six people died from the explosion or its effects. John DiGiovanni, a dental equipment salesman, was killed in the parking garage. Robert Kirkpatrick, a Port Authority structural engineer, and Stephen Knapp, a Port Authority maintenance supervisor, also died in the blast zone. Monica Rodriguez Smith, a secretary, and William Macko, a maintenance worker, were trapped and asphyxiated. Wilfredo Mercado, a Windows on the World receiving agent, suffered fatal injuries.
Emergency responders encountered zero visibility in stairwells, no working elevators, and thousands evacuating on foot. Some were trapped for hours. Pregnant women, people with respiratory conditions, and those on upper floors faced prolonged exposure to smoke. More than 1,000 people were treated for smoke inhalation, cuts, fractures, and trauma.
The vehicle identification number and the first break
Federal and local investigators combed through debris in the crater. On February 27, an ATF explosives expert located a vehicle fragment stamped with a partial Vehicle Identification Number. The fragment was traced to a Ford Econoline van rented from a Ryder agency in Jersey City, New Jersey, on February 25.
On March 4, Mohammed Salameh returned to the rental agency and attempted to reclaim his $400 deposit, claiming the van had been stolen. Investigators had already identified Salameh through rental records. He was arrested during a second visit to the agency. FBI agents and JTTF officers monitored him as he arrived to collect the refund check. His wallet contained business cards and phone numbers that became leads.
The VIN fragment was recovered within 24 hours despite catastrophic damage. That evidence led directly to Salameh and, through surveillance and financial records, to a wider network.
The investigation widens
Salameh’s contacts led investigators to a storage locker in Jersey City, where residue consistent with bomb-making materials was found. Chemical traces matched components used in the device. Telephone records showed repeated calls between Salameh, Nidal Ayyad, Mahmud Abouhalima, and Ahmad Ajaj in the months before the bombing.
Ramzi Yousef, the operational leader, had entered the United States on September 1, 1992, using a fraudulent Iraqi passport. He flew into JFK International Airport with Ahmad Ajaj, who carried bomb-making manuals in his luggage. Ajaj was detained. Yousef was admitted and later disappeared into the network planning the attack.
By mid-March, federal agents had arrested Salameh, Ayyad, Abouhalima, and Ajaj. Yousef fled to Pakistan hours after the bombing. He remained a fugitive for more than two years and continued planning attacks in the Philippines and elsewhere. He was captured in Islamabad in February 1995 and extradited to the United States.
Trial and convictions
The trial of Salameh, Ayyad, Abouhalima, and Ajaj began in September 1993 in the US District Court for the Southern District of New York. Prosecutors presented forensic evidence linking the defendants to the bomb materials, the van rental, and a Jersey City safe house where chemicals were mixed.
Nidal Ayyad, a chemical engineer, had ordered key materials and used his work computer to draft a letter sent to The New York Times claiming responsibility on behalf of a group calling itself the Liberation Army, Fifth Battalion. The letter demanded an end to US aid to Israel and intervention in Middle Eastern affairs. It was traced to Ayyad through computer forensics and word processing metadata.
In March 1994, all four defendants were convicted on charges including conspiracy, explosive destruction of property, and interstate transportation of explosives. Each received a sentence of 240 years in prison without the possibility of parole. Abdul Rahman Yasin, who mixed chemicals and assisted with the bomb, fled to Iraq and was never apprehended. Eyad Ismoil, who drove the van into the garage with Yousef, was arrested in Jordan in 1995, extradited, and sentenced to 240 years in 1998.
Ramzi Yousef stood trial separately in 1997. He was convicted on all counts, including murder and conspiracy to use weapons of mass destruction. At sentencing, US District Judge Kevin Duffy called the bombing an act of terrorism aimed at mass casualties and symbolic destruction. Yousef received life in prison plus 240 years. He is incarcerated at ADX Florence, a supermax facility in Colorado.
The blind sheikh connection
Omar Abdel-Rahman, an Egyptian cleric known as the Blind Sheikh, was investigated for his influence over the network. He was not charged in the 1993 bombing trial but was prosecuted in a separate case involving a broader seditious conspiracy to attack New York landmarks, including the Lincoln and Holland Tunnels and the United Nations building.
In 1995, Abdel-Rahman was convicted of seditious conspiracy and solicitation to murder Egyptian President Hosni Mubarak. Testimony and wiretaps introduced at trial showed he provided religious justification and spiritual direction to members of the conspiracy. He was sentenced to life in prison and died in federal custody in 2017.
Lingering questions and unresolved evidence
One contested detail involves the extent of the plotters’ ambition. Prosecutors and investigators concluded the bomb was intended to topple the North Tower into the South Tower, causing thousands of deaths. Yousef later told investigators he hoped to kill 250,000 people. The actual positioning of the van, combined with the bomb’s composition and yield, did not achieve structural collapse, but the intent remained central to sentencing arguments.
Questions also emerged about whether all participants were identified. Abdul Rahman Yasin fled the country and was reportedly seen in Baghdad in the late 1990s. His role in mixing the explosives was corroborated by other defendants, but he was never charged or tried. The FBI placed him on the Most Wanted Terrorists list, and his status remains unresolved.
Some intelligence analysts later pointed to the attack as an early signal of coordinated transnational terrorism. Ramzi Yousef’s uncle, Khalid Sheikh Mohammed, would later mastermind the September 11 attacks. Connections between participants in both plots were documented in commission reports and court filings, though no direct operational link was established in 1993.
Long-term impact on security and victims
The bombing prompted immediate changes in building security protocols and federal counterterrorism strategy. The Port Authority installed vehicle barriers, instituted stricter parking controls, and enhanced surveillance systems. The FBI and NYPD expanded the Joint Terrorism Task Force, increasing intelligence sharing and investigative coordination.
For survivors and victims’ families, the attack left physical and psychological harm. Many experienced chronic respiratory conditions tied to smoke exposure. Others suffered lasting trauma related to prolonged entrapment or witnessing the aftermath. Victim compensation processes extended for years, with litigation targeting building security and emergency response.
The World Trade Center was repaired and reopened, but the 1993 bombing remained a focal point in debates over vulnerability and preparedness. Those discussions intensified after the towers were destroyed on September 11, 2001. The memorial that now stands at the site includes the names of all six victims killed in 1993.
Where to look next
- Documentary: “Targeting the Towers” (National Geographic)
- Book: “1000 Years for Revenge: International Terrorism and the FBI” by Peter Lance
- Book: “The Cell: Inside the 9/11 Plot, and Why the FBI and CIA Failed to Stop It” by John Miller and Michael Stone
