A man who allegedly beat up two NYPD officers with a group of protesters on the Brooklyn Bridge over the weekend turned himself in on Thursday morning, police said.

Brooklyn resident and union organizer Robert Murray, originally identified as "suspect No. 3," was charged with several offenses, including second-degree assault, resisting arrest and obstructing governmental administration.

He turned himself in to Manhattan's fifth precinct at about 8 a.m. on Thursday, authorities said. He was arraigned late Thursday night, the Manhattan DA said.

Murray, 43, is accused of going in and out of the confrontation and pulling the officers down the ground. Murray, who was also arrested at a protest in 2004, then allegedly punched one of the officers twice "so hard that we have a witness that says that he heard the fist to the face."

"He's the individual that goes in and out of the confrontation," Manhattan Chief of Detectives William Aubry said at a news conference at police headquarters on Thursday. "His attacks were violent. And they were right up there with being one of the most violent acts that I've seen."

Murray was awaiting arraignment Thursday evening and could not be reached for comment.

Aubry said it appeared that two of the other suspects, a still unidentified man and woman, appeared to know each other. The reward for information leading to the arrests and convictions of the remaining six suspects -- three women and three men -- increased to $25,000 Thursday, Police Commissioner Bill Bratton said.

On Saturday, a group of seven protesters, including three women and four men, attacked two officers who were assigned to the NYPD's legal bureau, Bratton said earlier this week.

Bratton appealed to the public several times this week to help find those responsible, releasing photos of all seven suspects.

The two officers, Lt. Patrick Sullivan and Lt. Phil Chan, were attacked as they tried to arrest 29-year-old Eric Linsker, who was accused of trying to throw a garbage can onto the road, police said. Chan sustained a broken nose and Sullivan sustained multiple cuts and bruises during the altercation, police said.

"From the witnesses statements and the video, [Linsker] threw two garbage cans off of the walkway onto the roadway," Aubry said Thursday. "The actions of Lt. Chan coming on as the third can was about to be hauled over ... may have saved others from being injured."

While Linsker was able to initially run away, police said they found his backpack on the bridge, which contained a black ski mask, three hammers wrapped in plastic and a small amount of marijuana.