Dyner said a bathroom fan in a second-floor ceiling was sparking. He said he and other fraternity members grabbed fire extinguishers and tried to attack the fire in the attic, but they were forced back.

The fraternity previously practiced how to escape a fire, he said.

"Everything went perfectly according to plan," Dyner said.

About 40 to 45 firefighters from Normal and Bloomington were at the scene, Grussing said. There were no injuries among the firefighters.

Firefighters initially entered the building and reached the second floor, but they had to withdraw after about 10 minutes because of deteriorating conditions, he said. They then attacked it from the ground and ladder trucks.

The roof was gone and the second floor clearly appeared gutted from the exterior. Damage to the first floor was not as readily visible from the street.

The university's critical incident response team was called to the scene to arrange for the students' immediate needs of housing, food and clothing, ISU spokesman Jay Groves said. The team also will help students with longer-term needs such as replacement textbooks or arranging with professors to make up lost class work, Groves said.