SPRINGVILLE, Ala. (AP) _ A charter bus carrying about 40 schoolchildren on a field trip to an aquarium has overturned on a freeway near Birmingham.

State patrol spokesman David Richards says about 20 people were injured in the accident Friday. Most of them were students. None of the injuries was life-threatening.

Richards says the children were on their way to the Tennessee Aquarium in Chattanooga when the bus ran off the road, hit a guard rail and overturned.

The bus driver is among the injured. Two teachers were also on the bus with the children from Bryan Elementary School in Jefferson County, Ala.

Copyright 2008 The Associated Press.