WINDSOR, Ont. – A beaker explosion during a Grade 11 science experiment Tuesday sent a teacher and three students to hospital with cuts.

Fourteen other students, who were also in the class at F.J. Brennan Catholic high school, were sent to hospital for observation.

The school was placed on lockdown for a short time following the explosion, which occurred shortly after 10 a.m. in the class of teacher Steve Pellarin, said Jill Braido, a spokeswoman for the Windsor-Essex District Catholic School Board.

The teacher and his students were wearing safety glasses at the time and Pellarin, who was closest to the glass beaker, was the most seriously cut.

The teacher and students were taken to two Windsor hospitals while board officials and police inspected the glass-strewn classroom.

Braido said the experiment involved potassium chlorate, glycerine, manganese dioxide and sugar.

“It was a typical lab experiment,” said Braido. “Who knows today why there was a reaction?”

The explosion was “pretty traumatic” for those who saw it, she said. They’ll be offered counselling and were to be sent home for the rest of the day.

The entire class was sent to hospital for observation, to test their hearing and check for other issues that might not have been obvious following the blast, Braido said.

chip.martin@sunmedia.ca