WALDORF, Md. (AP) — Maryland State Police say an impaired driver hit a patrol car parked at a Charles County crash scene.

Police said in a statement Tuesday that troopers were at the scene of a crash on Route 301 in the Waldorf area on Monday night. Police say a Mazda MX-5 hit an unoccupied patrol car that spun into another patrol car where two troopers were sitting. Neither was injured.

Police say the Mazda driver, 75-year-old Ruth Runyan of La Plata, refused medical treatment, but troopers detected signs of possible impairment. Runyan is charged with driving under the influence, driving while impaired, failure to change lanes for an emergency vehicle and other offenses.

Police say 37 troopers have been hit this year during traffic stops, at crash scenes or in construction zones.