A Pennsylvania State Trooper was seriously injured when a drunk driver crashed into his car in Chester County early Thursday, police said.

Trooper Chad Burgwald, 24, assigned to the Avondale barracks, was sitting in a marked police vehicle in the median monitoring traffic along U.S. Route 1 near Bancroft Road in New Garden Township just before 1 a.m., police said.

Heather DeLong, 47, of Glen Mills was driving along Route 1 when she lost control, swerved into the median and crashed into Burgwald's car, police said.

The trooper was trapped in the car, police said, and had to be removed from the mangled vehicle by mechanical means. He was airlifted to Crozer Chester Medical Center, where he was listed in serious condition Thursday night.

DeLong, who was not injured, was arrested on charges of aggravated assault while driving under the influence.

She is being held in the Chester County Prison on $200,000 cash bail, police said.