GREAT BEND, Kan. (AP) – A central Kansas truck repair shop has lost about $5,000 worth of diesel fuel to thieves who’ve probably been draining the tanks of semis for several weeks.

Central Power Systems and Services in Great Bend Manager Ethan Rowley says employees found the tank nearly empty in one semi. Employees then checked the other five trucks awaiting repairs, and all had empty tanks. Rowley says each tanks holds 300 to 500 gallons.

Great Bend police believe the tanks were emptied over the past month while the trucks were on the lot.

Company officials say it’s the biggest theft since it opened for business in the 1950s.