New York City Mayor Michael Bloomberg on Monday promised a "fair and thorough" investigation after a groom was killed on his wedding day and two others were injured in an undercover police operation outside a city strip club.

"The community is outraged, and I am — to put it mildly — deeply disturbed, but until we find out exactly what happened, I don't want to prejudice the district attorney's case or any grand jury that the district attorney has empowered," Bloomberg said.

Bloomberg met with NYPD Commissioner Raymond Kelly and community leaders to discuss how undercover officers shot Sean Bell, 23, and two of his friends as they celebrated his last night as a bachelor outside of the Kalua Cabaret strip club in Queens, N.Y. early Saturday morning. Bell, who was unarmed, was set to marry his high-school sweetheart and the mother of his two young daughters later that day.

"Clearly they were victims, and at the moment, from what I know, there is no evidence whatsoever that they were doing anything wrong," Bloomberg said. "Period."

Bloomberg urged a speedy investigation by the district attorney. The mayor said only two of the officers and one civilian have been interviewed thus far.

Police could not question the officers who fired at the men because the district attorney must first complete an investigation, Kelly said.

Bloomberg spoke with Bell's fiancee by phone, as well as community leaders throughout the weekend to update them on the investigation and receive their feedback.

"We will tell everybody everything we know, when we know it and not speculate," Bloomberg said. "And we will go internally and look and see if our procedures and training can be improved."

The five officers who fired their weapons have been placed on paid administrative leave and have surrendered their weapons, the mayor said.

The officers will remain on leave "until we learn more about the circumstances of the shooting," said Paul Browne, chief NYPD spokesman. "There are still a number of unanswered questions."

The New York Post reported new details of the events, including how the undercover cop at one point climbing onto the hood of Bell's car — his gun drawn and his police shield around his neck — screaming, "Police! Turn off your car! Let me see your hands!" according to sources who talked to some of the cops involved in the shooting.

When Bell then tried to run down the plainclothes officer — twice — the cop began shooting, with some of his 11 bullets piercing the rear window of the man's Nissan Altima, the sources said.

This left the cop's backup unit — which was just arriving on the scene amid shattering glass and the undercover's shouts of "He's got a gun!" — thinking they were being fired upon from inside the vehicle. That's when they returned fire with another 39 bullets. One 12-year veteran, a narcotics detective, pumped 31 bullets, authorities said.

"It's hard to understand why 50-odd shots should be taken," Bloomberg said Monday. "To me that sounds excessive and unacceptable, but we'll wait and see for the investigation."

The sources recounted step-by-step how quickly things spiraled out of control after a dispute inside the club involving one of Bell's associates.

According to the sources, two undercovers were at the strip joint as part of the NYPD's new Club Enforcement Initiative. The program was started after the July slaying of 18-year-old Jennifer Moore of New Jersey, who partied at a New York club before being abducted, raped and killed in a Weehawken, N.J., hotel.

The undercovers, who usually worked in Manhattan, were on the last night of their two-month Queens detail to try to nail the Kalua and other clubs on such violations as drugs and underage prostitution.

Both officers were unarmed inside the club and one officer had two drinks, Kelly said. "The officers were not given Breathalyzer tests," Kelly said.

Department policy authorizes undercover officers to have two drinks, Kelly said.

Inside the club, one of the plainclothes cops sat next to a woman he thought was a hooker and might proposition him, the sources told the Post.

Suddenly, a burly man approached them and told the woman that he had heard she had gotten into a fight with a group of guys earlier in the club. It was unclear what it was over.

The man said, "'Don't worry, baby, I got you covered,' and he takes her hand, and he rubs it across [the gun in] his waistband," a source said. "Then he tells her, 'That's what I'm here for.'"

It's unclear how the man smuggled his weapon past the metal detector outside the club. He likely was a regular who knew the bouncer at the door and may have worked there part time, helping with security, the sources said.

The undercover then went outside the club and radioed his backup to tell them there was a man inside with a gun. It was around 3:30 a.m.

While the undercover was outside, the suspect came out along with the girl and others, since it was around closing time.

The undercover watched as an argument erupted between Bell's group, which included three male friends and the large man with the gun, and four other men — with the woman in the middle of them, the sources said.

The woman was overheard saying to the men arguing with Bell's pals, "I'm not doing you all. I'll do one or two, but not all," according to the sources.

Around the same time, the undercover said he heard Bell's friend Joseph Guzman tell his buddies, "Yo, get my gun! Get my gun! Let's get my gun from the car! Yeah, we're gonna f- - - him up!" the sources said.

The undercover, thinking there was about to be a drive-by shooting in front of the club involving Bell's group, followed Guzman, Bell and two others to their car.

"It's getting hot! Something's going to happen! Something's going down!" the undercover radioed to his backup.

He hurried to the front of Bell's Altima, which was parked on the side of a nearby street, and jumped in front of it.

That's when the undercover put his right leg up on the hood of the Altima and began screaming that he was a cop, the sources said.

The cop was leaning over the hood of the car to try to see the hands of the people inside and make sure they didn't have any guns, they said. But Bell floored the gas pedal and headed for the cop, the sources said, striking him and badly cutting his knee.

One of the Altima's passengers — who possibly had a gun — jumped out of the back of the car, the sources said.

Around the same time, an unmarked Toyota Camry driven by a plainclothes police lieutenant and another cop behind him pulled up, but overshot Bell's car. A police van with an officer and the narcotics detective then managed to block Bell's car in.

Bell's Altima first struck the police van in the driver's desperate bid to escape, then backed up and struck the roll-down metal doors of a commercial building behind him. He then revved his car again toward the undercover — which prompted the cop to scream, "He's got a gun!" and start firing, according to the sources, with the bullets passing through Bell's car.

"The undercover thought they had more than one gun. He thought they would do anything to get away. He was yelling, 'Let me see your hands!'" one source said.

The other cops, thinking they were under attack, started firing at the car, too.

"It is not the policy of the police department where a police officer can shoot at a car when the car is being used as a weapon, so at least in that case, it would appear that the policies of police department were broken, but we don't even know that because there were allegations of a gun," Bloomberg said. "We did not recover a weapon and we have been unable to so far to find people that were in the club where the two unarmed undercover officers were working."

At one point, the detective thought his gun had jammed and so reloaded his magazine and emptied the clip again at the car, firing 31 bullets.

Bell was killed, Guzman critically injured, and a third friend, Trent Benefield, was shot. They are expected to live.

Benefield later told a friend from his hospital bed that he and his buddies didn't know the undercovers were cops.

He told investigators, "I got into the car, and there was all this shooting."

It was unclear when the other four men who were originally fighting with Bell and his pals fled the scene. They were spotted leaving in a black SUV.

Bell had been arrested three times in the past: twice for drugs and one on a gun rap in a case that was sealed. Guzman has been busted nine times, including for armed robbery. He spent two stretches in state prison in the '90s. Benefield has a sealed record as a juvenile for gun possession and robbery.

Some marijuana was later found near the Altima, and investigators believe that it may have been tossed out by the group before the gunfire. Two bullet casings also were recovered from the Altima, although cops said they do not believe they were from a police gun.

The shooting of Bell, who was black, has ignited racial tensions in the city — even though the cops involved included two blacks, a Hispanic and two whites.

The five cops who fired shots were put on administrative duty. Commissioner Kelly said it was the first time that any of the officers were involved in a shooting.

Detectives Endowment Association President Michael Palladino said the cops were justified in firing off a total of 50 bullets at unarmed men because Bell was using his car as a lethal weapon.

"Once the threat ended, so did the shooting."

A source told The Post: "They [the cops] feel completely sad about what happened. They made a decision, and they're going to live with it."

On Sunday, the group 100 Blacks in Law Enforcement Who Care said it is issuing a vote of no confidence in Kelly. It also wants the removal of the Organized Crime Control Bureau chief, Anthony Izzo, who it says created the undercover unit involved in the incident.

Browne said Sunday, "We are continuing to look for additional witnesses to shed light on the incident and assisting the district attorney's office with its investigation."

Community leaders are planning a Dec. 6 rally at police headquarters.

"When a shooting like this occurs there are legitimate questions about it, and it's essential to the city to do fair and thorough investigation, to accept its consequences and to make sure everything is done to prevent future incidents like this from occurring," Bloomberg said.

FOXNews.com's Sara Bonisteel, the Associated Press and the New York Post contributed to this story.