Maryland State Police said a trooper was struck while inside his patrol vehicle by a driver suspected to be under the influence.

It happened Wednesday just after 1 a.m. The trooper was inside his marked car with the emergency lights on in lane 1 of a work zone on the Outer Loop of Interstate 495 and Greentree Road in Montgomery County.

Police said Nithya Ramani, 37, of Montgomery Village, drove into the work zone and struck the right rear of the patrol vehicle.

“After observing signs of impairment,” police arrested Ramani, who was not injured in the collision, a Maryland State Police news release said. She was charged with driving under the influence.

The trooper was not taken to the hospital. Maryland State Police did not identify the trooper.

The investigation into the crash is ongoing.