A 350-pound black man died after being clubbed repeatedly by officers in a videotaped beating that raised new allegations of police brutality against blacks in Cincinnati (search) nearly three years after the city was rocked by riots.

The mayor said Monday that the videotape showed that the nightstick-wielding officers were defending themselves.

The cause of Nathaniel Jones' (search) death on Sunday was under investigation. But preliminary autopsy results showed that the 41-year-old man had an enlarged heart, and his blood contained cocaine and PCP, or "angel dust," both of which can cause bizarre or aggressive behavior, Hamilton County Coroner Carl Parrott said.

Two black community activists said Jones' death was another example of brutality by Cincinnati police. The fatal shooting of an unarmed black man by a white officer in April 2001 set off three nights of rioting, but the streets were quiet Monday in the area where those riots were centered.

"How many of our people have to die before the city decides to do something about it?" said Nathaniel Livingston Jr. of the Coalition for a Just Cincinnati (search).

The videotape from a police cruiser's camera showed two white police officers landing at least a dozen blows with their nightsticks on Jones and tackling him, while shouting at him to put his hands behind his back. But the tape also showed Jones lunging at one of the officers.

The officers who were at the scene -- five whites and one black -- were placed on administrative leave, which is standard procedure.

After seeing the video, Mayor Charlie Luken rejected activists' demand that he force Police Chief Thomas Streicher Jr. to resign.

"What I saw was a 400-pound man violently attacking a police officer in a manner that put the lives of police officers at risk," Luken said. "While the investigations will continue, there is nothing on those tapes to suggest that the police did anything wrong."

The Rev. Jesse Jackson issued a statement Monday saying he wants state and federal authorities to investigate.

"Police officers have options available to immobilize citizens short of death," Jackson said.

Justice Department spokesman Jorge Martinez said Monday night: "We're in the process of gathering information and evidence to determine whether any federal action is warranted."

An employee at a fast-food restaurant had called 911 early Sunday to report that a man had passed out on the grass outside. Emergency personnel arrived and reported that the man was awake and "becoming a nuisance," according to police radio transmissions.

The first two officers to arrive, Baron Osterman and James Pike, were shown on the video striking Jones after he ignored orders to "stay back," took a swing at an officer and put his arm around an officer's neck.

Jones then fell forward onto the officer as the two momentarily went out of the camera's field of view.

The officers knocked Jones to the ground and fell on him, and jabbed or struck him with nightsticks at least a dozen times over several minutes until he was handcuffed. They kept yelling, "Put your hands behind your back!" as they struggled to handcuff him.

Additional police officers arrived. They rolled Jones onto his back and one officer was heard saying: "He's still got a pulse. I don't see him breathing."

Officers called for an ambulance. He died within minutes of arriving at the hospital, Assistant Chief Richard Janke said.

The Cincinnati chapter of the National Association for the Advancement of Colored People called for changes in police use of force.

"If proper procedure means that you can use that kind of force to clobber people repeatedly who are clearly disarmed, then there's something wrong with the policy," said Calvert Smith, chapter president.

Black activist groups staged an economic boycott of Cincinnati after the 2001 shooting of Timothy Thomas, 19, who was wanted on charges of fleeing police. Officer Stephen Roach shot him in a dark alley and was later cleared at trial of criminal charges.

A federal investigation of that shooting, requested by the city, resulted in a 2002 agreement by the city to tighten policies regarding use of force and to improve handling of citizen complaints against the police.

Last February, a white officer chased and fatally shot a black man who was spotted running from a store that had been broken into. Police, prosecutors and a citizen review panel concluded the shooting was justified because the suspect was beating the officer with his nightstick.