An NYPD detective publicly testified about his actions in the Sean Bell shooting for the first time Wednesday, and explained in his departmental trial that he thought one of Bell's friends was going for a gun.

Detective Gescard Isnora, seen above center, took part in a disciplinary hearing that could result in his dismissal.

He testified he had no doubt that Bell and his friend Joseph Guzman were going to shoot a man they were arguing with in the early morning hours of November 25, 2006.

On the stand, Isnora said while he was working undercover at a Queens strip club, he heard Guzman yell, "Go get my gun, go get my gun."

According to Isnora, Bell then yelled, "Let's f--- him up, let's f--- him up."

When Bell tried to drive off, Isnora said he was slightly clipped by Bell's car.

The detective said he yelled, "Police, don't move," and then testified, "I see Joseph Guzman reaching, clutching towards something."

"I yelled 'gun' and fired center mass into the car," Isnora continued. "I wasn't going to wait for him to have a gun. By then it is too late."

Eleven of the 50 bullets shot that night were fired by Isnora, Bell was killed hours before his wedding and Guzman and another friend of Bell were severely wounded.

Evidence shows there was no weapon in Bell's car.

Isnora and two other detectives were later acquitted of manslaughter in the shooting.

Bell's family sat in the front row of today's hearing to hear what Isnora would say.

"I've been waiting for five years to hear from the detective's mouth what was the reason that Sean is not here today," said Bell's fiancee, Nicole Paultre Bell, before the hearing.

Following the hearing, she said, "To me, it seems like the detective was paranoid.... You shot at innocent civilians, shot an innocent man, shot another innocent man 17 times and you call yourself a good guy."

"Just hearing him and looking at him, I was praying that he would look my way. He didn't. Just to see a mother's face still in pain, looking at him. I just kept my eyes focused on him," said Valerie Bell, the victim's mother.

Isnora said the last thing he wanted to do was fire his gun.

The detective's union says Bell and Guzman's actions caused the shooting.

"The facts are the same. If you keep reviewing the facts you get a better, clearer picture of who the good guys are and who the bad guys are," said Michael Palladino of the Detectives Endowment Association. "The detectives were out there in good faith, they were called there, duty called there. And in good faith they took the action that they had to take, as tragic as it may be."

The undercover officers were at the Queens strip club looking to arrest drug dealers and prostitutes and Bell was there for his bachelor party.

Officer Michael Carey, who did not face criminal charges, is also expected to testify.

An inspector with the firearm review board testified yesterday that the officers failed to follow guidelines and did not face an imminent threat when they opened fire on Bell's car.