Thieves were able to steal a forklift truck from a building site in Gloucester after using it to break through a set of gates.
Officers were called to the site in the Matson area on Saturday afternoon after the theft was discovered by a worker.
Detectives believe the red Manitou forklift, valued at £25,000, was taken sometime between 1300 and 1615 BST.
"The unknown offenders then made off in the forklift down Matson Lane," police said.
"Anyone who saw suspicious activity in the area on Saturday, or saw the forklift being driven away, is asked to contact police or Crimestoppers," the force spokesman added.