A hazardous-materials situation forced the evacuation early Monday morning of an Arizona State University building in Tempe.
Tempe Fire Department officials said that a biomedical experiment blew up after an ASU employee flipped a vacuum-pump switch in the Interdisciplinary Science and Technology Building on east Tyler Street.
The fire set off a sprinkler system, which alerted fire officials at 1:40 a.m.
Mike Reichling, a Tempe fire spokesman, said a gas buildup near the pump likely caused the fire. He added that the employee who flipped the switch received treatment for minor burns to one of his arms.