A few parents with students at Two Mile Prairie said they were concerned that the alerting system from the school was not working.

Michelle Baumstark with Columbia Public Schools said, "We sent out a mass alert to all of the parents who had children on the bus.  One hundred percent of the messages were received."

"We sent an alert as soon as we had enough information and were able to confirm the route and the students that were riding the bus."

The wreck happened right before 3:00 p.m. 

The medical crews arrived between 3:10 and 3:15.

It was then when Baumstark sent alerts to the parents of those on the bus.

A Highway Patrol Report showed four students were injured.