Officials have raised the number of Auburn, Massachusetts, police officers affected by high carbon monoxide levels to six and have pulled a total of 10 police cruisers and three other town-owned Ford vehicles.
Engineers from Ford will be testing Auburn's fleet of cruisers on Thursday.
Given the town's concerns, officers have now all been tested for carbon monoxide after an unidentified officer passed out in his cruiser Wednesday just before hitting another vehicle.
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All of the affected officers have since been released from the hospital.
Ford is experiencing similar problems with Explorers in other parts of the country. The company is now working with Auburn, but it says it's premature to conclude that higher-than-normal levels of carbon monoxide are to blame.
Auburn is looking to install carbon monoxide detectors in its cruisers; however, it will be at least two weeks before those detectors are available in the department's fleet.
Police Chief Andrew Sluckis plans on providing an update on the investigation later Thursday.