Officials are unsure what started a fire that caused 5,000 students and employees to evacuate from the Memorial Union Thursday afternoon.
Mike Reichling, a Tempe fire spokesman, said the department believes the fire started in one of the restaurant kitchens on the second floor.
ASU spokeswoman Leah Hardesty said the MU would be closed at least through Friday so the Tempe Fire Department could complete its investigation.
The air quality within the MU was still poor as of late Thursday afternoon, she added.
"Our most important concern is the safety of our students," Hardesty said. "We are pleased to hear that everyone has been evacuated safely."
All occupants were successfully evacuated from the building, including four wheelchair-users who were carried out, Reichling added. No one was treated at the scene for smoke inhalation, he added.
Judy Schroeder, an MU program coordinator, said the building's fire sprinklers, located only in the basement and in Pitchforks Restaurant on the first floor, did not go off.
More than 60 firefighters from Tempe, Mesa and Phoenix, along with Tempe and ASU police officers, responded to the two-alarm fire after 911 dispatchers received the call at 12:48 p.m., he said.
The fire was upgraded to a two-alarm fire after the on-scene fire chief determined the need for more manpower, Reichling added.
Although students reported the smell of burned plastic and a hazardous material crew responded to the call, Reichling said the structure fire was not considered a hazardous material assignment.
But the building suffered significant damage and would remain closed indefinitely, he added.
The fire provided the first opportunity for the University to use its new text messaging alert system, she said.
The system was implemented Sept. 28 following security changes made after the Virginia Tech tragedy.
Students who voluntarily signed up for the notification system received a text message that said the fire had been contained and everyone had been evacuated.
Kendall Warden, a psychology senior, said she received the message at 1:55 p.m., more than an hour after the fire broke out and more than half an hour after firefighters had contained the blaze.
The University sent out an e-mail notifying the campus community of the fire and its containment at 3 p.m.
Hardesty said the University also updated its Web site to let people know the MU would be closed until further notice.
Reach the reporter at sarah.g.owen@asu.edu.
