The blaze was at the impound yard operated by the Policía de Tránsito. The Cuerpo de Bomberos said that the lot contained 220 vehicles and 500 motorcycles.
The alarm came in just a few minutes before noon. Fire fighters from Parrita, Quepos and Garabito responded and had the blaze under control within an hour.
The fire agency said that subsequent investigation showed that the blaze started in a car that was parked near a fence along a public road. The car did not have a battery, so fire fighters concluded that someone caused the blaze.
They have turned the case over to the Judicial Investigating Organization.
Last Feb. 26 fire fighters quenched a grass fire in the same location, they said.
The Policía de Tránsito impounds a vehicle for a number of reasons, including drunken driving, expired plates and serious traffic violations.