HARTFORD, Conn. (AP) — Hartford police are urging car dealerships and auto repair shops to tighten security because thieves have been breaking in to steal keys which they use sometimes days later to steal vehicles.

Deputy Chief Brian Foley says the department is investigating six such burglaries into dealerships in the city since July.

In one break-in, 56 keys were stolen. The suspects were arrested two days later as they entered the property to steal vehicles.

In some cases vehicles were used to drive over and through the dealership fencing.

Police have sent a letter to 198 dealerships and repair shops in the region urging to them to take additional security measures, including investing in surveillance systems and keeping vehicle keys in lock boxes out of sight of customers.