MEXICO CITY – Hundreds of police officers dressed in riot gear stormed the town of San Juan Ixtayopan southeast of here until the early hours of Thursday, kicking down doors and arresting 33 suspects in Tuesday’s brutal burning deaths of two federal police officers.

The massive operation, which began late Wednesday and involved elite officers wearing night vision goggles and ski masks and backed by helicopters, contrasted sharply with the lack of response Tuesday when a mob beat three officers before dousing two of them with gasoline and setting them on fire.

The third officer was rescued when reinforcements arrived more than three hours after the attack began.

The arrested included four men suspected of providing the gasoline and matches.

Police used photos and video clips taken by news crews to identify the suspects, many of whom were pulled from their homes by the hair in the middle of the night.

There was still no explanation as to why police took so long to respond to calls for help from the officers, who were beaten for nearly two hours before being set on fire. News crews dispatched from central Mexico City, 40 miles away, arrived hours before the first police reinforcements.

“I can’t understand why, given how long those acts took, there wasn’t a quicker reaction by authorities,” Attorney General Rafael Macedo de la Concha said Thursday at news conference.

Macedo said his office was investigating local and federal agents as well as Fatima Mena, the mayor of the municipality of Tlahuac, where San Juan Ixtayopan is located.

Several hundred agents and mounted police continued to patrol the town Thursday. Residents put a sign at the kiosk where the rescued officer, Edgar Moreno, had been tied up about to be burned.

It read: “Innocent or guilty, police or civilians, nobody has the right to take someone’s life, much less the way it was done.” Moreno remained in critical condition at a Mexico City hospital.

The three officers, members of the Federal Preventive Police, were dragged from their car outside the Popol Vuh elementary school, as afternoon classes finished, when children and residents screamed they were child kidnappers.

Mexico City’s judicial police officials said Thursday that the three were investigating 27 accusations, most of them about small-time drug trafficking but including five child kidnappings.

Neighbors on Thursday made public a letter sent to municipal leader Mena two weeks earlier about a “suspicious group” in a gray car videotaping children at the elementary school and a nearby day care center.

Several residents told police that a family-operated candy business across from the school in reality was selling drugs to children.

Meanwhile, authorities continued to blame traffic for the delay in getting reinforcements to San Juan Ixtayopan.

“We would have liked to have gotten there a lot earlier,” said Marcelo Ebrard, Mexico City’s secretary of public security. “You can’t move 600 men in helicopters.”