OXFORD, Miss. (AP) – Students at the University of Mississippi questioned the school’s fire safety procedures as investigators returned to a charred fraternity house Saturday to find the cause of a fire that killed three people.

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

“We 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.

The house was cordoned off so investigators could continue their work Saturday, and a university spokesman said work was likely to continue throughout the weekend.

The spokesman, Mitchell Diggs, said a memorial service was planned, but no date had been set.

Killed in the fire were Howard Stone, 19, of Martinsville, Va.; William Townsend, 19, of Clarksdale, and Jordan Williams, 20, of Atlanta. All three were sophomores.

Chancellor Robert Khayat said Friday that the prevailing feeling on the campus “is sadness, pain, and sorrow and regret.”

The university enacts fire safety policies at school residences, but not fraternity houses, said Jeff Alford, vice chancellor for university relations. The ATO house had no sprinkler system.

Krisha Garmon, 28, who lives in student housing down the street from the charred house, 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.”

Firefighters needed about two hours to bring the fire under control, chapter adviser Al Bell said. Alford said officers responding to the fire heard the alarms, which apparently were working.

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 said 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.

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

Officials said the fire appeared to have started in the dormitory wing in the southeast corner of the ATO house. The victims were found in that wing – two in the basement and one on the floor above, said Randy Corban, chief of university police.

The university has an enrollment of about 14,000, and more than one-third of the student body belongs to fraternities or sororities.