When a hijacked jetliner crashed into Tower 1 of the World Trade Center, many electricians were wiring tenant spaces in the top floors of the 110-story Twin Towers. Down below, engineers and other contractors were working in their sublevel offices.

Jim Usher, vice president of communications for E-J Electric Installation Co., a Long Island City electrical contractor, was one of them.

His office had recently moved from Tower 5 to the sublevel of Tower 2. On the morning of Sept. 11, he was working downstairs in his office when he heard a deafening explosion and smelled gunpowder, which he realized later was jet fuel.

“The plane went into Tower 1 and at the time, I was in Tower 2 underground,” Usher said. “When the first explosion occurred, I went to our engineering office to advise our folks there.”

Engineers gathered together and discussed what happened. E-J built the new security system after the 1993 World Trade Center bombing, and the engineers were able to monitor the security system and review footage.

“They started to pull it up on the cameras to see what had happened because at this point, no one knew that it was an airplane that had gone into the building,” Usher said.

When Usher suspected that it was a bomb, his priority shifted from reviewing the security tapes to getting his team out of the building.

“I told them to stop trying to find out what happened and just immediately evacuate the building,” Usher said. “I didn't know it was an airplane, but it was obviously a huge explosion.”

Many electricians and engineers then heeded Usher's warning and evacuated. Usher, however, stayed behind to alert the other contractors in “Shantytown,” a slang term for the contractors' offices in the sublevel of Tower 2.

“I went back because it dawned on me that there were 10 or 12 contractors' offices down there right in a row,” he said. “A whole pile of other contractors down there didn't have a clue. I was concerned that if and when the evacuation over the PA ever happened, it wouldn't be announced down there in the basement levels since the PA only works mainly in the concourse, the tenant floors and the towers.”

Usher then banged on all the closed doors to make sure everybody knew that there was an explosion and they needed to evacuate. When he came upstairs, he found total chaos.

“People in Tower 2 had come down and there was some confusion as to whether or not they should evacuate,” Usher said. “There was conflicting information going over the PA system.”

Many people were hanging around in the lobby wondering whether or not they should exit the building. Usher helped the security officers deliver one message — GET OUT.

“I told them to evacuate — ask questions later, but just get the hell out,” Usher said.

Usher then tried to exit the building onto Liberty Street, but the exit was blocked.

“Two World Trade faced out to Liberty Street,” he said. “That exit had already been closed off because at this point, stuff was flying through the air. It was all over the place. They did not want people exiting there.”

Some people took an escalator up to the plaza level, but it had been blocked off as well.

“When I went up to the escalator and realized there was no way I was going to exit out onto the plaza, I did a U-turn and went back down,” Usher said. “I walked down around 2 World Trade lobby again and then came back out on the main concourse of the mall level.”

Usher then directed everyone out of Tower 2 and down to the east side of the complex so they could exit through 4 and 5 World Trade. He then finally got himself out of the building.

“I went out on to Liberty Street at 4 World Trade,” he said. “Debris was still falling, but it was more on the paper side. It was not hunks of metal or anything dangerous. The visibility was horrible. Obviously, people were panicking, yelling, screaming and running all over the place.”

Usher then discovered two injured men on Liberty Street and helped carry them into an infirmary on the ninth floor of Deutsche Bank, which is directly across from 2 World Trade.

“I took the first man up the stairs and into the doors and then jumped on the elevator,” he said. “I went up to the infirmary and there were a couple of nurses and a doctor there. I dropped him off and went back down to get his buddy.”

Usher then walked back down to Liberty Street, where he heard the second hijacked plane roaring above him. He quickly picked up the other man and carried him up the stairs to the entrance of the bank.

“When I got up about 15 steps, that's when the plane went into 2 World Trade,” Usher said. “That was scary.”

At this point, debris was flying through the air, he said.

“I had to run for cover, so I went up another five steps to the top,” he said. “There was no way that I could make it up to the building.”

Instead, he crouched down by a waterfall, he said.

“I put the waterfall between the Trade Center and me,” Usher said. “Hunks of steel were flying through the air. I knew that if we got hit, that was the end of us. I laid down on top of the guy for a minute and all this stuff came down.”

Some of the employees and customers of the bank had still not evacuated the building when a jetliner slammed into Tower 2.

“They were standing inside the plaza looking out at 1 World Trade and by now, of course, they are looking at the plane going into 2 World Trade,” he said. “The guys opened the door and a couple of them yelled, ‘Make a run for it.’”

The second explosion worsened the visibility, Usher said.

“It was very hard to see,” he said. “You could tell it was just paper and concrete. Smashed up concrete was still flying down, but there weren't the big hunks of steel, which is what I was concerned with.”

Usher then carried the man up to the infirmary. When he went back down to the street, Tower 2 collapsed, Usher said.

“When 2 came down, I was standing on Liberty Street by 2 World Trade,” he said. “You knew it was a matter of time before it would come down, but you didn't know if it was going to be one minute, one hour or 10 hours.”

The sheer heat generated by the explosion was a sign that it was going to eventually collapse, Usher said.

“You knew it was coming down because of the huge fireball,” he said. “I felt a tremendous blast of heat when I was on the street after the plane went into Tower 2.”

Usher recalls that it was about a half an hour before it finally came down.

“When it started to topple, you heard it,” he said. “You knew it was coming down, but it was so engulfed with all the concrete, dust, a cloud of smoke and the black stuff that you did not have a clue as to which direction it was going to fall. At that point, I literally told the folks to run for their lives. I did likewise. I ran south of the tower toward the Staten Island Ferry.”

Usher said he ran 10 or 15 blocks to escape from the scene.

“You heard the thing coming, but you didn't want to turn around and look,” he said. “Once I got down 10 or 15 blocks, I turned around and I looked. I knew it had come down, but I still couldn't see it because of tremendous smoke and dust.”

Rather than falling sideways, the tower crashed straight down to the ground.

“I knew it didn't fall toward me,” he said. “I was worried at that point about the domino effect — if it is going to fall on another building, which would fall onto another building. At that point, I did not know that it had imploded.”

When the plane slammed into Tower 2, Usher realized that the World Trade Center was under a terrorist attack.

“When we heard that the plane had gone into Tower 1, we didn't even think of a terrorist attack,” he said. “We heard it was a little plane. Everyone made the assumption that it was a four- or six-seater and something happened to the pilot and it flew in. Nobody even knew that the plane penetrated the building.”

The explosion in Tower 2, however, made Usher realize it wasn't an accident.

“When I saw the whole thing on No. 2, it was obvious that it was a terrorist attack,” he said. “It didn't take a rocket scientist to figure it out. I saw the plane go into Tower 2 and then a fireball erupted.”

All of his coworkers made it out, but about 16 IBEW Local #3 members were still missing.

“It was a horrific event and Local #3 has suffered a huge loss,” Usher said.

The electricians were wiring tenant spaces on the 100th floor and above when the plane crashed into Tower 1, Usher said.

“Those people didn't stand a chance to get out of Tower 1,” he said. “There was no way that they were going to make it.”

If it wasn't for Usher, more people may have been trapped in the building, said E-J President Tony Mann.

“He's very modest, but he got out but then helped injured people,” Mann said.

Usher said he only did a fraction of what other rescue workers did to save lives.

“There's been a tremendous outpouring of people, both professionals and volunteers, that have literally worked around the clock to find any more survivors,” Usher said. “I did nothing compared to what other people did.”