Seven people were killed and four others were injured Thursday night when a large truck rear-ended a minivan on the Indiana Toll Road near Middlebury, police said.

Police believe the driver of the minivan may have slowed down or stopped after hitting a deer in the eastbound lanes of the toll road at around 8 p.m. The truck crashed into the back of the minivan, which was carrying 10 passengers.

Seven passengers in the minivan were pronounced dead at the scene of the crash. The three other passengers and the truck driver were transported by helicopter and ambulance to local hospitals for treatment.

The toll road was closed for four hours while police investigated the crash.