Thursday marks the 22nd anniversary of the 1993 bombing of the World Trade Center, and an often-overlooked section of the September 11 Memorial and Museum details that first terror attack. NY1's Michael Herzenberg filed the following report.

A 1,200 pound bomb detonated, ripping a hole a half a football field wide and several stories deep beneath the north tower of the World Trade Center.

"We were trying to reach the people that were trapped on different levels," a firefighter at the scene told NY1. "We could hear them screaming."

Forty- to 50,000 people were inside the World Trade Center. Some were stuck in elevators for nearly 12 hours.

Civilians helped. At the time, it was the largest city rescue effort ever.

Six people were killed. A thousand were hurt. More than half of them required hospitalization.

It was a wet, snowy day just after noon on February 26, 1993.

On the day of the explosion, then-Police Commissioner Ray Kelly said, "We have not determined the origin of this explosion." But by the next day, officials suspected a bomb, and after 48 hours, investigators had recovered parts of a van that exploded in the garage. Two of the pieces had a vehicle ID number.

One of the bombers foolishly returned to the Jersey City business where he rented the van. The FBI arrested him. 

Six people eventually were convicted in the terror attack.

"This was not a suicide mission," said Jan Ramirez, chief curator of the September 11 Memorial and Museum. "They detonated the fuse and left."

The museum details the events leading up to the 1993 and 2001 attacks, and shows some of the little-known links between them, including a laptop that conspirator Ramsey Yusef used in the mid-1990s trying to figure out a way to smuggle explosives onto American passenger jets.

"It was then that the idea occurred to him that they didn't actually need to smuggle explosives onto the planes," Ramirez said. "They would simply use the planes as targets of mass destruction."

Another little-known fact: The 1993 bombing remains an open criminal case. The seventh alleged conspirator, Abdul Yasin, is at large.

All of this information and more is available at the museum and at this link.