Mpls. school evacuated after science classroom explosion

A north Minneapolis high school was evacuated Monday morning after an explosion in a science classroom.

Cherie Penn, assistant chief of the Minneapolis Fire Department, said crews were called to Patrick Henry High School at about 9:30 a.m. after a report of a chemical explosion.

"When they arrived there they found an injured male teacher [with] minor injuries, burns and cuts, and some damage to a table and some chairs in the science lab in a classroom," Penn said.

Penn said the teacher was preparing for a classroom demonstration when the explosion occurred.

"It was a combination of a crystallized form of hydrogen peroxide, hydrogen chloride, and acetone," Penn said. "These chemicals had been mixed and prepared several days in advance."

No students were in the classroom at the time of the explosion. The injured teacher was taken to North Memorial Medical Center for treatment of minor burns and cuts.

Evacuated students were allowed back into the school at around 11:15 a.m. Monday is the first day of classes for public schools in Minneapolis.