A breakdown in command structure and poor officer communication led to the violent confrontation between Los Angeles police and thousands of peaceful demonstrators at a May Day rally, officials said in a preliminary report released Tuesday.

Using radio transmissions, video footage and dozens of interviews from command staff, Los Angeles Police Department investigators painted a picture of a chaotic scene.

Among the findings were that there was no person clearly in charge, command staff at a remote location ordered the use of rubber bullets in another location, and orders to the crowd to disperse were never clearly announced before force was used.

"Clearly, leadership was lacking. It was sorely missing," Police Commission President John Mack said in a press conference after a commission meeting in which top brass presented a nearly two-hour overview of the preliminary investigation.

"Things just got out of control."

At least 23 protesters and nine members of the media were injured May 1 after riot-clad LAPD officers used rubber bullets and battons to clear MacArthur Park during a mostly peaceful immigration rally.

Broadcast images of officers hitting reporters and shooting non-lethal bullets into a crowd that included women and children led Mayor Antonio Villaraigosa to cut short a trade mission to Mexico and Central America and scarred relations between the LAPD and immigrant communities.