The explosion happened around 1:15 p.m. in the Old Main building, said Olympia Fire Capt. Kate McDonald, who described it as an ethanol vapor explosion.

34 students were in the room at the time for a demonstration. They were trying to show the different burn rates of gases. They were comparing propinol and ethanol.

During the experiment, the big glass containers of the two gases are lit and students get to watch the burn rate.

"It's actually a really cool experiment," said chemistry student Jose Avila. "As the gas burns, it makes a beautiful flame as it goes up the bottle. It just didn't do what it has always done."

Chemistry student Melissa Chalker adds: "They did the propinol OK and then the ethanol one just exploded, the whole thing just shattered. Everyone was just standing there in shock."

Glass from the two containers shattered all over the place, cutting several of the students. Five were taken to the hospital to be treated and another five were treated at the scene.

The students say it was a simple experiment gone wrong. But it is big enough of a deal to cancel classes for the rest of the day to allow investigators to figure out how a simple chemistry demonstration went very wrong.

"It's an accident. It happens," said Avila. "They'll change some procedures and I hope they do it again."

The fire and police departments are investigating the explosion. At this point, they don't know what went wrong on an experiment that reportedly is done quite often in science classes with no problem.