MINNEAPOLIS — A graduate student has suffered serious burns in a lab explosion at the University of Minnesota that prompted the building to be evacuated.

Minneapolis Fire Department crews were sent to Smith Hall around 1:10 p.m. Tuesday. Crews arrived to find one person suffering from burns after a volatile chemical compound exploded.

Authorities said the grad student at the College of Science and Engineering was conscious with serious burns, and was taken to Hennepin County Medical Center. No other details about the student’s condition were immediately available.

Crews evacuated the building, monitored for hazards and sealed the lab. About 50 people were evacuated. The building reopened about 5  1/2 hours later.

The fire department said there was no fire or structural damage. The cause of the explosion is unknown.