Three New York police officers who killed an unarmed man in a 50-shot barrage outside a seedy strip club hours before his wedding will not face civil rights charges, federal authorities said Tuesday.

The parents and former fiancee of Sean Bell, along with the Rev. Al Sharpton, had lobbied federal prosecutors in Brooklyn to charge the officers with violating Bell's civil rights.

"After a careful and thorough review, a team of experienced federal prosecutors and FBI agents determined that the evidence was insufficient to prove, beyond a reasonable doubt, that the law enforcement personnel who fired at Bell (and two friends, Joseph Guzman and Trent Benefield) acted willfully," the Justice Department said in statement. "Accordingly, the investigation into this incident has been closed."

U.S. Attorney Benton Campbell met with Bell's family members Tuesday to tell them. Guzman, Benefield and Bell's fiance, Nicole Paultre Bell, were to appear at a news conference later Tuesday.

The family "will not stop our pursuit of justice in this matter until every measure in the criminal and civil arena has been exhausted," Sharpton said in a statement. "Fifty shots on an unarmed man who engaged in no crime is intolerable."

An attorney for one of the New York Police Department officers called it "the right decision."

Accusing the officers of federal crimes after a state court acquittal "would have been a real stretch," said the lawyer, James Culleton. "Everyone should move on."

Bell, a 23-year-old black man, was killed and his friends were seriously injured outside Kalua Cabaret in Queens in 2006 as they were leaving his bachelor party by car. The officers, all undercover detectives, had been investigating reports of prostitution at the club.

No weapon was found in Bell's blood-splattered, bullet-riddled car.

The shooting sparked community outrage and accusations that the New York Police Department was too quick to use excessive force against minorities.

At a non-jury trial in 2008, prosecutors portrayed the officers as trigger-happy cowboys. They accused one of the shooters, undercover detective Michael Oliver, of firing 31 of the 50 total shots — even pausing to reload.

An undercover working with the accused officers testified that they became alarmed after witnessing a heated argument outside the club between Bell's friends and another patron who appeared to have a gun. He claimed they overheard Guzman, say, "Yo, go get my gun."

In grand jury testimony, Detective Gescard Isnora said that he decided to follow Bell, Guzman and Benefield to their car because he believed they were going to commit a drive-by shooting.

Guzman denied saying anything about a gun; other witnesses also testified that the dispute ended peacefully. He and Benefield also testified that they never heard the officers yell warnings before opening fire and tried to drive away because they feared for their lives.

Isnora gave a different account: When he confronted the men, he only resorted to deadly force after Bell bumped him with the car and smashed into an unmarked police van, and after he spotted Guzman make a sudden move as though he were going for a gun.

A judge ended up acquitting the three shooters of state charges that included manslaughter, assault and reckless endangerment. The Justice Department said afterward it would review the incident, though a civil rights case was always considered a long shot.

Police Commissioner Raymond Kelly said Tuesday that the decision clears the way for the NYPD to pursue administrative charges against the three detectives and one other shooter who wasn't charged in the criminal case. He declined to comment further.

The family also has filed a wrongful death lawsuit against the city.