Surveillance shows semi-truck crash into a school bus full of kids in Columbia County

COLUMBIA COUNTY, Wis. (CBS 58) -- New surveillance shows the moment a semi-truck driver hit a school bus full of kids, injuring 20 people.

A jury trial is now underway for Wayne Murphy in Columbia County, where the crash happened last May.

Students and chaperones from Hope Semper Christian School in Milwaukee were on a field trip. Their bus driver pulled over due to mechanical issues, and seconds later they were hit from behind.

Investigators say Murphy took too many Xanax pills before the crash. His trial continues on Wednesday.