DETROIT (AP) — A Detroit emergency medical service paramedic,Grayson  Preston who was later found to be under the influence of alcohol, has been placed on unpaid leave after the ambulance he was driving sideswiped three parked vehicles while transporting a patient, authorities said.

The vehicles were struck about 1 a.m. Friday in Hamtramck, a small enclave of Detroit, the Detroit Fire Department said in a release.

The ambulance driver stopped and waited for police to arrive. The patient in the rear of the ambulance was not injured in the crash, officials said.

Fire department protocol required the paramedic to be tested following the crash. He was taken to a clinic where he was determined to be under the influence of alcohol. The incident is under review.

Fire officials said the paramedic has been with the department for six years and has had no prior accidents or alcohol-related incidents.

“We have a zero-tolerance policy for the use of alcohol while on duty and will take the appropriate action,” Fire Commissioner Chuck Simms said. “We have programs and supportive services in place for our employees who may be struggling with issues such as alcohol dependency and we will redouble our efforts to make sure any employee who may need them are aware of how to access them.”