History: Collapse Of The World Trade Center, September 11, 2001, Lower Manhattan, New York City, United States

• February 26, 1993 bombing
On February 26, 1993, at 12:17 p.m., a Ryder truck filled with 1,500 pounds (680 kg) of explosives, planted by Ramzi Yousef, detonated in the underground garage of the North Tower. The blast opened a 100 foot (30 m) hole through five sublevels with the greatest damage occurring on levels B1 and B2 and significant structural damage on level B3. Six people were killed and 50,000 other workers and visitors were left gasping for air within the 110 story towers. Many people inside the North Tower were forced to walk down darkened stairwells that contained no emergency lighting, some taking two hours or more to reach safety.
Yousef fled to Pakistan after the bombing but was arrested in Islamabad in February 1995, and was extradited back to the United States to face trial. Sheikh Omar Abdel Rahman was convicted in 1996 for involvement in the bombing and other plots. Yousef and Eyad Ismoil were convicted in November 1997 for their carrying out the bombing. Four others had been convicted in May 1994 for their involvement in the 1993 bombing. According to a presiding judge, the conspirators' chief aim at the time of the attack was to destabilize the north tower and send it crashing into the south tower, toppling both landmarks.
Following the bombing, floors that were blown out needed to be repaired to restore the structural support they provided to columns. The slurry wall was in peril following the bombing and loss of the floor slabs that provided lateral support against pressure from Hudson River water on the other side. The refrigeration plant on sublevel B5, which provided air conditioning to the entire World Trade Center complex, was heavily damaged. Subsequent to the bombing, the Port Authority installed photoluminescent markings in the stairwells. The fire alarm system for the entire complex needed to be replaced because critical wiring and signaling in the original system was destroyed. As a memorial to the victims of the bombing of the tower, a reflecting pool was installed with the names of those who had been killed in the blast. However, the memorial was destroyed following the September 11 attacks. Names of the victims of the 1993 bombing are included in the National September 11 Memorial & Museum.