A Utah school bus driver has been arrested on suspicion of DUI after swerving lanes and nearly hitting a car on a busy stretch of highway while taking 67 elementary-school students on a field trip.

Utah Highway Patrol Sgt. Blaine Robbins said Monday that authorities suspect Lycia Martinez had taken prescription anti-anxiety/muscle-relaxer pills.

Robbins says a motorist and a parent on the bus made 911 calls about the erratic driving.

Davis School District spokesman Chris Williams says Martinez has worked for the district for six years. She's on paid leave during the investigation.

Martinez doesn't have a listed phone number, and it's unclear if she has an attorney yet.

The fifth- and sixth-graders made it to a student council conference at Brigham Young University after another driver shuttled them the rest of the way.