There was an explosion at Tampa's Jefferson High School recently. The small blast sent students running for cover. There were no serious injuries. Tampa police arrested three 15 year old students and charged them with arson and throwing a destructive device. Jefferson High, like hundreds of other schools around the country, is on alert for school violence.

Senior Kristin Foster said the explosion sounded like a gunshot. ``Everybody scattered. They were running and crying. Everybody was scared'' she said. Other Tampa area schools have experienced an unusual number of bomb threats recently. Police believe the explosive device was a container filled with acid. Hillsborough County school officials say there were over 50 bomb threats in county schools during the 2000 - 2001 school year. Said parent Bernice Chaberier, whose son is a junior at Jefferson, ``I want to know what they are going to do about this. It's terrifying. I had to leave work twice last week because my kids were scared after the bomb threats, and now this.''