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.

LAPD Chief William Bratton told the commission Tuesday that the violence was an "aberration" that could not be minimized.

"The main reason for the controversial action - the large use of non-categorical use of force in response to an environment of rock and bottle assaults on our officers from a small group of agitators that did not appear to be a part of the rally or its organizers - was quite simply a command and control breakdown," Bratton told the commission.

"It began at the planning stages and dominoed throughout the event itself."

In the first clear timeline of events of the day, First Assistant Chief James McDonnell outlined the problems that unfolded over two hours - beginning when protesters reached the park's far southeastern edge and ending when officers cleared the park by hitting protesters with batons and firing more than 140 rounds of rubber bullets.

In his review, McDonnell found there was no clear incident commander for the more than 500 officers that were deployed.

Radio transmissions also show confusion among officers as to who was giving orders and commands.

Capt. John Egan of LAPD's Rampart Division was supposed to be the incident commander, but Cmdr. Cayler "Lee" Carter made many of the decisions on the ground, McDonnell said.

Carter was demoted and placed on home assignment one week after the melee. Cmdr. Louis Gray, who McDonnell said cleared officers to use non-lethal weapons, was reassigned to the Operations Bureau.

Bratton said he expects to make more personnel changes in the coming weeks as the internal investigation into the actions of individual officers continues.

An independent inspector general has also launched an investigation. The FBI also is investigating possible civil-rights violations.

"The report represents an update and is far from over as far as determining what happened and who is being held accountable for actions at the scene," said Villaraigosa.

According to the timeline of events, tensions between officers and agitators first erupted around 4:28 p.m. when officers issued a radio call for help at Alvarado and Eighth streets.

"Officer in trouble, officer in trouble," one policeman can be heard saying in a radio transmission.

It was unclear what was occurring but one protester was arrested at 4:40 p.m. for climbing a pole to videotape jubilant marchers chanting as they headed toward the park.

"While the vast majority of this crowd was made up of peaceful individuals exercising their First Amendment rights, a group of agitators verbally assaulted officers," McDonnell said.

Over the next 30 minutes, McDonnell said, no other incidents were reported. But by 5 p.m., several agitators had moved closer to the park and some were near the western side of the park near Park View and Wilshire Boulevard.

In response, LAPD officers shut down Wilshire Boulevard, which runs east and west along the Southern side of the park, and called more officers.

The scene became increasingly tense as some agitators threw bottles and rocks at officers near Seventh and Alvarado on the east side of the park.

The report makes no mention of thousands of people who had gathered inside the park where there was a festival-like atmosphere for the immigration-rights rally that had been under way for hours. Thousands gathered there were oblivious to the skirmishes and escalating tensions occurring on the fringes.

As tensions rose, one officer was knocked off his motorcycle along Wilshire Boulevard around 5:12 p.m.

Around 5:45 p.m. on the west side of the park, organizers were trying to quell anger among some in the crowd by using a sound truck to clear agitators.

Meanwhile, along the east side of the park, police were requesting extra officers to deal with a hostile atmosphere as agitators began to converge in that area.

By 6 p.m., discussion began about shutting down the event. Carter, Gray and Egan met. It's unclear who made the determination to finally declare an unlawful assembly.

"They've been throwing things at us nonstop for the last few minutes. I think that qualifies. Let's get units down here," one officer said over the radio.

A minute later there was a request for an LAPD helicopter to make an announcement to disperse the crowd. But the chopper was not equipped so another request was made for a sound truck to make the announcement.

"We were taking rocks and bottles, we're not going to stand here and continue to take them just because ... they are not doing it now," another officer said over the radio.

An additional request for personnel was made but the command center said none could be given because earlier in the day, LAPD commanders had taken off two squads of Metropolitan Division officers that had already policed an immigration march. Only the "B platoon" trained in crowd control was left - along with more than 400 additional officers from surrounding divisions.

Top commanders were positioned in various locations in the park, with Egan and Gray on the west side near Park View, Capt. Tom McDonald five blocks away at the command center, and Carter heading toward the center of the skirmishes.

By 6:09 p.m., Carter had joined officers on the south side of the park where the disturbances were taking place. He notified the command post that officers from Metropolitan Division would respond to the disturbances.

Radio transmissions captured a discussion between two sergeants in the metro unit.

"My understanding from the incident commander is he is making the entire park an unlawful assembly and wants the entire park dispersed," one said.

Orders to disperse had been given overhead by a helicopter but were difficult to hear.

At 6:17 p.m., metro officers in riot gear stormed the park.

In video footage, officers can be heard ordering people in English to leave the park immediately but McDonnell said that protesters were not given evacuation routes, time to leave or warnings on what would happen if they did not.

As police moved through the park, several officers were captured on video striking protesters with batons and shooting about 140 rubber bullets into the crowd.

By the end of the demonstration, five arrests had been made. Since then, just a juvenile and a man identified only as Marcus Keton have been charged. Keton pleaded guilty to throwing a substance at a vehicle.

The City Council is scheduled to consider the report today. [MORE]