Three detectives were found not guilty Friday on all charges in the shooting death of Sean Bell, who died in a hail of 50 police bullets outside a club in Jamaica, Queens, in November 2006. The verdict prompted calls for calm from the mayor, angry promises of protests by those speaking for the Bell family and expressions of relief by the detectives.

Detective Michael Oliver, who fired 31 bullets the night of the shooting and faced manslaughter charges, said Justice Arthur J. Cooperman had made a “fair and just decision.”

Justice Cooperman delivered the verdict in State Supreme Court at 9 a.m. Describing the evidence, he said it was reasonable for the detectives to fear that someone in the crowd that night carried a gun. He added that many of the prosecution’s witnesses, including Mr. Bell’s friends and the two wounded victims, were simply not believable. “At times, the testimony of those witnesses just didn’t make sense,” the judge said.

Several supporters of Mr. Bell stormed out of the courtroom, and a few small scuffles followed outside the courthouse. By midafternoon, there were no suggestions of any broader unrest around the city. Mr. Bell’s family and fiancée left without making any comments and drove to visit his grave at the Nassau Knolls Cemetery and Memorial Park in Port Washington.