On February 6 1993 at 12:18 pm there was an explosion at the World Trade Center (tower 1). Smoke filled the building. elevators shut down, trapping people inside. Many people were injured, and the damage to the building made it hard for rescue workers to do their job. The rescue effort was mostly focused toward the garage. People couldnt see because of the smoke, and they couldnt use the elevators, so they had to attempt to make it down the stairs blinded and chocking on smoke. Many people died from smoke inhalation. At first it was thought that there was a fire, or transformer, but high activity on police channels made it clear that it was something more. The Vista Hotel also received damage. The blast was strong enough to blow through 4 levels of the parking garage, up the street, and higher. During the rescue efforts 6 people were found dead. One of which was Monica Smith, who was pregnant with her first child.
As the FBI analyzed the damage it became very clear, even early on, that this was caused by a very powerful bomb.They thought it was most likely place in the basement, on one of the parking levels, most likely inside a vehicle.
Other Sources
World Trade Center Bombing 1993