An explosion occurred during preparations for a classroom experiment on the first day of school Monday at Patrick Henry High School in north Minneapolis, fire officials said.
The teacher suffered minor cuts and burns from the incident, which occurred about 9:30 a.m., said Assistant Fire Chief Cherie Penn.
Some chairs and a table were damaged but nothing caught fire, Penn said.
The school in the 4300 block of Newton Avenue N. was immediately placed in lockdown and then evacuated once fire personnel and a hazardous-material crew arrived, the assistant chief said.
The all-clear was given less than two hours later.
The teacher, whose identity has yet to be released, was "breaking apart a crystal that reacted violently" during an introduction to the class, said school district spokeswoman Emily Lowther. The teacher was being treated at North Memorial Medical Center in Robbinsdale. There were no other injuries.
PAUL WALSH
