The images are chilling: A young man, his face bloody and swollen, struggles to tell a television reporter that he is an undercover federal agent, then a mob burns him and another officer alive on camera.

The horrific footage from the killings Tuesday night put a spotlight on growing vigilante justice in Mexico, where police are viewed as inept at best and corrupt at worst and where many people say they must take security into their own hands as crime soars.

Mexican authorities responded to the police deaths Wednesday night as about 500 federal agents stormed the San Juan Ixtayopan (search) area, sealing off streets and mounting a house to house search for mob ringleaders.

Witness said several people were arrested within minutes but officials were unavailable to confirm how many people were detained.

The officers' deaths came amid rumors that children had been kidnapped from an elementary school in San Juan Ixtayopan, a neighborhood of 35,000 people on Mexico City's southern outskirts. When people saw three men taking photos Tuesday and staking out the school, they took action.

One after another, residents set off dozens of crude, rooftop bullhorn alarms that serve as a backup security measure in some poor districts. Neighbors poured into the streets, where they cornered and then beat the men. Onlookers cheered and shouted obscenities.

Reporters arrived, and the assailants pushed the victims before TV cameras so they could be interviewed. Barely conscious and struggling to talk, they nodded and gave one-word answers when asked if they were federal agents.

As television helicopters hovered overhead, police arrived. One agent was rescued, carried away unconscious by his arms and legs. He was in critical condition Wednesday evening, authorities said.

The other two officers were soaked with gasoline and set ablaze, their charred bodies left in the street as dozens of people milled around.

The federal police director, Adm. Jose Luis Figueroa (search), said the three plainclothes agents were in the neighborhood to investigate drug dealing near the school.

Talk focused on the police themselves. Others said vigilante justice is to be expected in a country where police are infamous for seeking bribes and often implicated in the same crimes they are supposed to prevent.

Mexico City Police Chief Marcelo Ebrard said local police who were on the scene Tuesday couldn't control the crowd until reinforcements arrived.

"The problem was that there were more than 2,000 people, angry, out of control, at night," he said.

There appeared to be little remorse in San Juan Ixtayopan, a picturesque community tucked into pine-covered hills at the foot of a snowcapped volcano.

Before Wednesday night's raid, people milled about in the central plaza, discussing the bloodshed. Vendors loudly hawked tabloid newspapers carrying photos of the victims and boldfaced headlines that screamed "LYNCHED."

Many people were reluctant to speak to reporters. Some denied being present during the beatings. Others said they stayed up through the night crying after trying unsuccessfully to stop the assault.

But some residents complained police had ignored reports of the kidnappings and said they did not regret what had happened.

"If the police aren't going to do anything, then the town has to take matters into their own hands," said 15-year-old Maria Eva Labana, who said she witnessed some of the attack firsthand before she ran home to watch the rest on TV.

Figueroa said a heavy case load had kept authorities from concentrating on the purported kidnappings. Community leader Mario Rios said he had received no reports of kidnappings and knew nothing of children disappearing. Several parents interviewed at the school said they had heard rumors of disappearances but knew of no actual cases.

Residents had been on edge, however, saying they reported seeing strange men who also claimed to be federal agents taking photographs of schoolchildren a couple of weeks ago, but never heard anything more about it from local police.

Most Mexicans believe they must protect themselves from crime.

San Juan Ixtayopan has only 12 police officers, or about one for every 3,000 residents, said Melquiades Martinez, an official with the Federal Preventative Police (search). Local officials said they distributed the bullhorn alarms, which are equipped with flashing red lights, to help people feel safer.

Earlier this month in another town on the capital's outskirts, police rescued a 28-year-old man residents were threatening to beat to death for allegedly trying to steal a guitar and tape deck from a community center. Two years ago, a mob killed two of three youths who allegedly tried to rob a taxi driver in Mexico City.

"Anarchy is growing, broadening, proliferating in different areas of the country," said Jose Antonio Crespo, a political analyst.