LOS ANGELES (AP) -- The FBI opened an investigation Thursday into video footage of a police officer repeatedly striking a suspect in the face during a struggle on a Hollywood street.

The officer and his partner described repeated blows to the suspect's face in their written arrest report, as well as efforts by the man to resist and their concern that the man might grab one of their guns, according to the document obtained by The Associated Press.

Federal investigators initiated a civil rights inquiry after the video from the three-month-old incident came to the bureau's attention Thursday, FBI spokeswoman Laura Eimiller said.

The footage, shot by an area resident, shows two officers holding down William Cardenas, 24, on a sidewalk as one punches him several times in the face before they are able to handcuff him. The struggling suspect yells repeatedly, "I can't breathe!"

The Police Department has begun its own criminal and administrative investigations into the officers' use of force during the Aug. 11 arrest, said police spokesman Lt. Paul Vernon. The officers were identified as Alexander Schlegel and Patrick Farrell, and both have been reassigned to administrative work.

"There's no denying that the video is disturbing," Chief William Bratton said at a news conference. "But as to whether the actions of the officers were appropriate in light of what they were experiencing and the totality of the circumstances is what the investigation will determine."

Vernon said Cardenas, a known gang member who had been wanted on a felony warrant for receiving stolen property, ran after police encountered him. After catching up to him, the officers knocked him to the ground.

The officers wrote in their arrest report that Cardenas tried to throw them off as they tried to handcuff him. At one point, the report said, an officer felt his gun holster being tugged on.

The other officer then struck the right side of Cardenas' face, and three more blows followed, the report states.

"The suspect continued to attempt to fight us by grabbing at my partner's waist," according to the report, provided by Cardenas' lawyer.

"The suspect's hand covered my partner's gun holster so I yelled at my partner to watch his gun. My partner responded by capping his gun and delivering a left elbow to the suspect's face causing the suspect to let go of him," it said.

With Cardenas still resisting, one officer used pepper spray on him, but that had "little effect," the report said. The officers were able to handcuff him only after two of his friends arrived and told him to stop fighting, according to the report.

Cardenas, who was held without bail, faces charges of resisting arrest. He suffered cuts and bruises on his arms, leg and face, and received stitches on an eyelid.

Gary Ingumenson, independent counsel for the Los Angeles Police Protective League, which provides legal representation for officers, said he welcomed the investigations, contending the officers acted well within their rights and department policy. In particular, police appeared to use what are known as "distraction strikes," a tactic for subduing suspects, he said.

"This would have never happened if the suspect had surrendered as he is lawfully obligated to do," Ingumenson said.

Cardenas' attorney, B. Kwaku Duren, accused the officers of violating his client's civil rights and claimed department investigators were stalling.

"I think the LAPD is being caught covering up an obvious excessive use of force," he said.

Authorities learned of the video footage, which has been posted on YouTube.com, when the defense made it public Sept. 14 during Cardenas' preliminary hearing, police said. The district attorney's office is reviewing whether to continue with the Cardenas case, which is scheduled for trial Nov. 20, said spokeswoman Jane Robison.