"I think it is necessary to make sure people know everything is in order and we will conduct a thorough and transparent investigation," the mayor said late Thursday in Mexico. He's expected back in Los Angeles on Friday afternoon.
Criticism of Tuesday's police action at MacArthur Park grew Friday — as did the potential legal and political consequences from the scenes of rallygoers and journalists being struck by officers. Even the city's police chief has questioned whether his officers overreacted.
Eight police officers were hurt; investigators are still trying to determine the number of civilians who were injured.
CBS Radio correspondent Steve Futterman reports that the FBI is conducting a preliminary inquiry into the actions of police, and whether the civil rights of the protestors were violated.
Police Chief William J. Bratton said he hoped a federal review would show the department has nothing to hide while dispelling any claims that police targeted immigrants or immigrant rights activists.
At least three other investigations are under way — two by the LAPD, one by the civilian oversight committee.
Sacramento Hinojosa dodged police firing rubber bullets, then, he says, they knocked him down and stepped on him, cutting his hand and twisting his ankle.
"I don't know why the police come and push me like this. I don't do nothing bad," Hinojosa told CBS News correspondent Bill Whitaker.
KTTV-TV news camerawoman Patti Ballaz has filed a lawsuit seeking unspecified damages against the city and police. The claim alleges civil rights violations, said Kathy Pinckert, a spokeswoman for Ballaz's attorneys.
Ballaz has a fractured wrist and injuries to her ankle, and was hit in the breast with a police baton, Pinckert said. She's also suffering from insomnia and mental distress, Pinckert said.
State legislators, immigration activists and others gathered Friday at MacArthur Park to denounce police conduct.
"There are no excuses. A simple apology is not going to suffice," said state Assembly Speaker Fabian Nunez. "To say we are outraged is an understatement. We want those responsible in the highest levels of the LAPD to pay consequences."
Nunez said the department's handling of the rally should be considered in determining whether Bratton should be given another five-year contract.
"I don't think you heard anybody say Chief Bratton is immune to any of this," Nunez said.
Bratton has expressed "grave concern" about police conduct at the rally and promised a full investigation. He has said the use of force began while officers were dealing with 50 to 100 "agitators" and that objects were thrown at officers.
Victor Narro, an attorney with the National Lawyers Guild who helped organize Tuesday's event, said police had promised to keep him abreast of any potential trouble but his liaison, a police captain, was unreachable.
The guild is reviewing videotape and determining whether to sue the Police Department. He noted that in one tape he saw police fire a rubber round at a boy who appeared to be 10 and "toss him aside like a piece of meat."
The police union says the whole story isn't on the videotape.
"I'm concerned right now with that there's a rush to judgment," Los Angeles Police Protective League President Bob Baker told Whitaker, "which is troubling to me and, to be quite frank, is very appalling."
John Mack, president of the Police Commission, the civilian overseers of the Police Department, told reporters the clash was "a terrible breakdown" and the panel wants to get to the bottom of who was in charge at the time.
"We have a responsibility to protect individuals while they're expressing themselves," Mack said.
The MacArthur Park melee occurred with the mayor away on a city mission to Central America. Villaraigosa was in El Salvador at the time and continued the trip after video and photos of the incident began to show its scope. His staff said he was in constant contact with police and other officials.
"I was very disturbed by what I saw," Villaraigosa told reporters in Mexico City, where he arrived Thursday.