On February 26 1993, a powerful explosion tore through the foundations of the World Trade Center in Lower Manhattan, killing six people, including a woman who was seven months pregnant, and injuring over 1000. Fifty thousand people were evacuated from the damaged buildings. The blast left a crater 200 by 100 feet wide and five stories deep, and caused the ceiling of the mezzanine of the adjacent Port Authority Trans-Hudson (PATH) train station to collapse.
An FBI expert on explosives described the blast as “the largest improvised explosive device that’s been in the U.S. since we started doing forensic explosive investigations in 1925.” 
Explosives experts estimate that the bomb which caused the explosion weighed approximately 1000 pounds, and the price of the chemicals used to make it cost slightly more than $400.
Several days after the explosion occurred, police and federal officials made their first arrest in the case. Tracing the VIN (vehicle identification number) found on a piece of metal at the site of the explosion, investigators were led to Mohammed Salameh, a 25-year-old illegal alien from Jordan who allegedly rented the yellow Ford Econoline van which was used in the bombing.
Salameh, together with the two other suspects who were arrested – Nidal Ayyad and Ibrahim Elgabrowny – all participated in demonstrations on behalf of El Sayyid Nosair. A fourth suspect who fled this country, Mahmud Abu Halima, is believed to be head of a HAMAS terrorist cell.  Halima is believed to have fled to Pakistan.