It took about four minutes for the plastic soda bottle to bubble, explode and splash acid on the ground and across a wooden wall.

The Salt Lake City Police Department bomb squad set off several explosions Tuesday at a training center near the Salt Lake City International Airport to demonstrate the danger of chemical and dry-ice bombs.

"This stuff here makes us nervous because it's so unpredictable," said bomb squad Sgt. Carl Merino as he waited for the soda bottle to explode.

The demonstration occurred less than a week after two men and three women were arrested and jailed for allegedly setting off acid bombs on the football field at West High School.

Merino said police take about 30 to 50 reports a year of similar explosions in the city. Usually it's teenage boys, he said, who make and explode the bombs. But it's not treated as the high school prank it once was, he said.

"You can blow off fingers and damage hearing," he said.

To prove the point Tuesday, bomb squad officers also covered a dry-ice bomb with a large red bucket. After about two minutes, the bucket shot into the air about 15 feet, simultaneously ripping into large pieces. The same thing happened with a dry-ice bomb placed in a white metal mailbox.

Earlier in the day, bomb officers were setting off chemical bombs that exploded anywhere between five seconds and 21 minutes, Merino said.

"This is the unpredictable nature of them," he said.

Being in possession of a homemade chemical or dry-ice bomb in Utah is a third-degree felony. The charge can be enhanced to a second- and even a first-degree felony depending on where the bomb is detonated and if injuries occur, Merino said.

Police also passed around a handout that showed victims of homemade bombs with missing finger tips and thumbs, and one man with a face injury where a bottle cap shot into his forehead.

Merino said people sometimes don't take homemade bombs seriously because they are made with chemicals and household items, but they can cause serious harm, especially if a person is hit with shrapnel or sprayed with acid.

"We take it seriously," Merino said.