NASHVILLE, Tenn. - Two people were killed Thursday when an ambulance ran into the back of a state work truck stopped in the emergency lane on a Nashville highway.

Police said the ambulance was on a non-emergency trip to return a woman to her nursing home after a dialysis appointment.

The ambulance ran into the back of Tennessee Department of Transportation truck, killing the ambulance driver, 36-year-old off-duty Franklin firefighter David Cline, and 78-year-old patient, Sue Bly. An off-duty firefighter tending to the patient was seriously injured. The truck driver suffered minor injuries.

Police were investigating why the ambulance was in the emergency lane. The highway work truck was painted fluorescent green and equipped with multiple flashing lights, though it wasn't known if they were on.

The ambulance was operated by Rural/Metro, a private company that serves Middle Tennessee counties.

The company is cooperating with authorities in the investigation, Nick Diliberto, division general manager, said in a statement. Rural/Metro will also review the crash, he said.

"Our thoughts and prayers go out to the families" of those killed and for a speedy recovery of the two injured workers, the statement said.

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