Students at the University of Mississippi (search) questioned the school's fire safety procedures as investigators returned to a charred fraternity house Saturday to find the cause of a blaze that killed three people.

Twenty students and a house mother escaped the fire at the two-story, brick-and-wood frame Alpha Tau Omega (search) house on Friday.

"We are going to do everything humanly possible to identify what may have happened here," Mark R. Chait, who heads the Bureau of Alcohol, Tobacco, Firearms & Explosives office in New Orleans, said Saturday.

University spokesman Jeff Alford said the university enforces fire safety policies at school residences, but not fraternity houses. The ATO house had no sprinkler system.

Krisha Garmon, 28, who lives in student housing down the street, said that while evacuation routes are posted at her building, "I've lived in the village four years and we've never had a fire drill."

The house had undergone a routine fire inspection Aug. 17 that found problems including a lack of fire extinguishers in the kitchen area, paint stored in the basement and doors blocked with mattresses, Alford said. No citation was issued to the fraternity.

On Friday, firefighters needed about two hours to bring the blaze under control, chapter adviser Al Bell said. Hours later, smoke billowed out of where the roof had been, and much of the upper floor was in ruins.

Fred Cummings, a member of the Ole Miss cross country team who was out running at 6 a.m., said the smoke was so thick "it would choke you up" a mile away. "When we saw it, the flames were about two stories above the building," he said.

A fraternity member who was not at the house when the fire occurred said fellow members told him they woke up coughing and found smoke "everywhere."

"They said they just ran out as fast as they could, to get out of that building as fast as possible," said Sean Weidlein, of Middleburg, Va.

Alford identified two victims as William Townsend, 19, of Clarksdale, and Jordan Williams, 20, of Atlanta, both sophomores majoring in accounting.

Also missing was Howard Stone, 19, of Martinsville, Va., a sophomore political science major. The body of the third victim had not been identified Saturday.

Alford said authorities believed the fire started in the fraternity house's living area, but the cause was not immediately known.

Wynn Smiley, Alpha Tau Omega's national CEO, said contractors had been scheduled to meet Friday morning to address deficiencies found during the fire inspection.

"The things that couldn't be taken care of by the guys in the house were being talked about with the general contractor," Smiley said.

Ole Miss has an enrollment of about 14,000, and more than one-third of the student body belongs to fraternities or sororities. The fire occurred about a block from "fraternity row," where most of the frat houses are located.