A crash in Dane County involving a school bus snarled traffic on Tuesday morning.

It happened after 8:30 a.m. on the west-bound Beltline in Madison.

Police say a County Highway vehicle rear-ended the bus, starting a chain reaction, involving another school bus and two more cars.

At least three students on the first bus had minor injuries.

The students were from a school in Monona and were on their way to a field trip.