A medical transport plane has been grounded after it was struck by a bullet at a Mississippi airport.

WAPT in Jackson reports that a pilot for Physicians Air Transport was standing in a hangar at Hawkins Field in Jackson when he heard a loud ping. Soon after, the pilot found a bullet hole in the plane and evidence that a bullet has struck part of the airplane’s engine.

The incident reportedly happened before 6:30 p.m. Monday,  David Hood, the lead pilot for the air transport company told WAPT.

The 1993 Beechcraft aircraft flies emergency medical service missions in the U.S., Canada and Mexico.

Hood said it could cost $250,000 and take at least a week to get the plane back in the air.