A fire killed 35 children in a day care center in northern Mexico despite desperate attempts of firefighters and a father who crashed his pickup truck through the wall to rescue babies, toddlers and others trapped inside.

The building had only one exit, according to the fire department official, who spoke on condition of anonymity because he was not authorized to speak publicly about the fire. He said firefighters pulled children through the only door and through large holes that a civilian knocked into the walls before rescue crews arrived.

Noe Velasquez, an employee at a nearby auto parts store who helped pull out five toddlers, said the father of one of the children rammed his pickup truck through a wall.

"I didn't sleep last night. I've never gone through anything like that in all my life," he said Saturday.

The death toll rose to 35 after several children died overnight. At least 41 children and six adults were hospitalized after Friday's fire in ABC day care in the city of Hermosillo, Sonora state Gov. Eduardo Bours said. The adults included staffers at the day care and civilians who tried to help. Some of the children had third-degree burns, an Hermosillo fire department official said.

One child was flown to the Shriners Hospital for Children in Sacramento, California, the governor said. Others were sent to a hospital in Guadalara that has a special burns unit.

There were about 142 children in the day care at the time, with ages ranging from six months to 5 years, and six staffers to look after them, Bours said at a news conference Saturday.

The ratio is in keeping with legal standards, said Daniel Karam, the director of Mexico's Social Security Institute, which outsourced services to the privately run day care.

He said a May 26 inspection found that the building — a converted warehouse — complied with safety standards. Asked if the single exit constituted a safety code violation, Karam only repeated that the building passed the inspection, although he conceded that the security requirements might have to be re-evaluated.

"We always have to be open to improvements, especially when we have a tragedy that has so moved us," Karam said.

Velasquez said he and several other people rushed to the day care when they saw smoke. Teachers already had lined up some of the children outside but the very smallest were trapped, some in their cribs. Velasquez said he pulled out limp toddlers without knowing if they were dead or alive.

The fire started at an ajoining tire and car warehouse leased by the state government, Bours said. The blaze eventually spread to the roof of the day care, sending flames raining down on the children, the fire department official said.

Firefighters took two hours to control the blaze, the cause of which was still unconfirmed. Most of the victims died from smoke inhalation.

Sobbing parents flooded hospitals, desperate for news about their children.

Police trucks on Saturday cordoned off the block surrounding the salmon-and-blue day care, a cavernous building with a few, small windows mounted high up on the walls.

Forensic investigators gathered material, searching for clues to what started the blaze.

Photographs showed the sidewalk outside the day care strewn with upturned, slightly blackened baby seats and cribs in the immediate aftermath of the blaze. Cribs also could been seen through large holes punched through the walls.

The Mexican government sent a team of 15 burn specialists, three air ambulances, and other medical equipment, President Felipe Calderon said. He ordered an investigation by Mexico's attorney general.

Building safety violations have been blamed for previous disasters in Mexico.

In 2000, a fire killed 21 people at a glitzy Mexico City disco that only had one available exit, lacked smoke detectors and did not have enough fire extinguishers. Many of the dead were found near the club's emergency exit, which was locked with a chain. More than 140 nightclubs were closed for code violations after that fire.

Last year, 12 people died in a botched police raid at another Mexico City nightclub. Officers blocked the overcrowded club's lone working exit, creating a deadly stampede in which nine patrons and three police died in the rush to get out. The emergency exits had been blocked.