NEW YORK - Three detectives were acquitted of all charges Friday in the 50-shot killing of an unarmed groom-to-be on his wedding day, a case that put the NYPD at the center of another dispute involving allegations of excessive firepower.

Justice Arthur Cooperman delivered the verdict in a Queens courtroom packed with spectators, including victim Sean Bell's fiancee and parents, and at least 200 people gathered outside the building.

The verdict provoked an outpouring of emotions: Bell's fiancee immediately walked out of the room. His mother cried.

Outside the courthouse, which was surrounded by scores of police officers, many in the crowd began weeping as news of the verdict said. Others were enraged, swearing and screaming "Murderers! Murderers!" or "KKK!"

Bell, a 23-year-old black man, was killed in a hail of gunfire outside a seedy strip club in Queens on Nov. 25, 2006 his wedding day as he was leaving his bachelor party with two friends.

Officers Michael Oliver, 36, and Gescard Isnora, 29, stood trial for manslaughter while Officer Marc Cooper, 40, was charged only with reckless endangerment. Two other shooters weren't charged. Oliver squeezed off 31 shots; Isnora fired 11 rounds; and Cooper shot four times.

The officers, complaining that pretrial publicity had unfairly painted them as cold-*lo**ed killers, opted to have the judge decide the case rather than a jury.

The judge indicated that the police officers' version of events was more credible than the victims' version. "The people have not proved beyond a reasonable doubt that each defendant was not justified" in firing, he said.

A conviction on manslaughter could have brought up to 25 years in prison; the penalty for reckless endangerment, a misdemeanor, is a year behind bars.

The case brought back painful memories of other NYPD shootings, such as the 1999 shooting of Amadou Diallo an African immigrant who was gunned down in a hail of 41 bullets by police officers who mistook his wallet for a gun. The acquittal of the officers in that case created a storm of protest, with hundreds arrested after taking to the streets in demonstration.

The mood surrounding this case has been muted by comparison, although Bell's fiancee, parents and their supporters, including the Rev. Al Sharpton, have held rallies demanding that the officers two of whom are black be held accountable.

Still, a phalanx of police officers, some uniformed and some in the department's community affairs polo shirts, was stationed outside the courthouse Friday. The building was ringed by metal barricades. Some in the crowd wore buttons with Bell's picture or held signs saying "Justice for Sean Bell." After the verdict was read, some in the crowd approached officers but were held back; the jostling quickly died down.

After the verdict, Police Commissioner Raymond Kelly acknowledged that some people were disappointed with the acquittals.

"We don't anticipate violence, but we are prepared for any contingency," he said.

The nearly two-month trial was marked by deeply divergent accounts of the night.

The defense painted the victims as drunken thugs who the officers believed were armed and dangerous. Prosecutors sought to convince the judge that the victims had been minding their own business, and that the officers were inept, trigger-happy aggressors.

None of the officers took the witness stand in his own defense. Instead, Cooperman heard transcripts of the officers testifying before a grand jury, saying they believed they had good reason to use deadly force. The judge also heard testimony from Bell's two injured companions, who insisted the maelstrom erupted without warning.

Both sides were consistent on one point: The utter chaos surrounding the last moments of Bell's life.

"It happened so quick," Isnora said in his grand jury testimony. "It was like the last thing I ever wanted to do."

Bell's companions Trent Benefield and Joseph Guzman also offered dramatic testimony about the episode. Benefield and Guzman were both wounded; Guzman still has four bullets lodged in his body.

Referring to Isnora, Guzman said, "This dude is shooting like he's crazy, like he's out of his mind."

The victims and shooters were set on a fateful collision course by a pair of innocuous decisions: Bell's to have a last-minute bachelor party at Kalua Cabaret, and the undercover detectives' to investigate reports of prostitution at the club.

As the club closed around 4 a.m., Sanchez and Isnora claimed they overheard Bell and his friends first flirt with women, then taunt a stranger who responded by putting his right hand in his pocket as if he had a gun. Guzman, they testified, said, "Yo, go get my gun" something Bell's friends denied.

Isnora said he decided to arm himself, call for backup "It's getting hot," he told his supervisor and tail Bell, Guzman and Benefield as they went around the corner and got into Bell's car. He claimed that after warning the men to halt, Bell pulled away, bumped him and rammed an unmarked police van that converged on the scene with Oliver at the wheel.

The detective also alleged that Guzman made a sudden move as if he were reaching for a gun.

"I yelled 'Gun!' and fired," he said. "In my mind, I knew (Guzman) had a gun."

Benefield and Guzman testified that there were no orders. Instead, Guzman said, Isnora "appeared out of nowhere" with a gun drawn and shot him in the shoulder the first of 16 shots to enter his body.

"That's all there was gunfire," he said. "There wasn't nothing else."

With tires screeching, glass breaking and bullets flying, the officers claimed that they believed they were the ones under fire. Oliver responded by emptying his semiautomatic pistol, reloading, and emptying it again, as the supervisor sought cover.

The truth emerged when the smoke cleared: There was no weapon inside Bell's *lo**-splattered car.