HOUSTON -

A freak accident during a summer school science class at HISD's Scarborough High School left several students injured.

A small explosion brought the fire department to the school Thursday morning where they found lots of smoke, no fire, and a couple of students with minor injuries.

Just after 9am Thursday, the school started filling with smoke.

"We just heard a big boom noise and then an alarm came on," said one student. "Yeah, we thought it was a practice, but it was real."

Two students were mixing sugar with potassium in a science class and got the beaker they were using to do it too close to an open flame. One of those students is Elizabeth Gonzales.

"It exploded. We were doing an experiment and it exploded," Gonzales said.

Either hot glass or chemicals landed on her arm. The other students caught some of it too, but they weren't seriously burned.

"The Houston Fire Department showed up, cleared the building, made sure everything was safe in the lab. They treated two students for skin irritations," said Jason Cathings with Scarborough High School.