A state trooper was injured in a three-car crash Tuesday on the Turnpike southbound in East Windsor that snarled traffic during rush hour, according to police. 

According to a preliminary report, a trooper assigned to the Regional Operations Intelligence Center was responding to a report of a ladder in the left lane of the Turnpike in East Windsor Township around 4:24 p.m., said Trooper Christopher Kay, a state police spokesman. The trooper turned on his emergency lights and slowed down, as did a Chevrolet Impala behind him.

The car behind the Impala, a Volkswagen Jetta, did not slow down and rear-ended the Impala, pushing it into the Trooper’s unmarked car, Kay said.

The trooper, who officials did not identify, was released after being treated for neck and back pain at Robert Wood Johnson University Hospital Hamilton, Kay said. The driver of the Impala complained of shoulder pain at the crash but refused treatment. There were no other injuries.

The crash backed up traffic about four miles and cleared out around 6:30 p.m., according to the Department of Transportation.

No summonses have been issued, and the investigation is ongoing.