NEWTOWN, Conn.  — A tractor-trailer carrying 44 dairy cows crashed on a Connecticut highway exit ramp early Thursday, killing eight of the animals immediately while another six had to be euthanized because of their injuries, state police and agriculture officials said.

Police and firefighters responded to the wreck on an exit off Interstate 84 westbound in Newtown at about 3:30 a.m. and found the truck tipped over on the driver’s side. The driver was not seriously injured, firefighters said.

Authorities summoned a state veterinarian, who decided six other cows needed to be put down. State troopers euthanized the animals at the scene, police said.

The remaining 30 cows were doing well after having been loaded onto another truck and taken to a veterinarian for evaluation, the state Department of Agriculture said.

It wasn’t immediately clear what caused the crash. State police were investigating.

The truck was transporting the cows from Maine to Ohio, state agriculture officials said. There is a 24-hour diner and gas station off Exit 10, which has a ramp with a sharp curve.

State police closed the westbound side of the highway for several hours.