AUSTIN, Texas — Calling all cars, calling all cars. Be on the lookout for a late model ambulance with sirens flashing.

Texas police are hunting for a man who hijacked an ambulance while the crew was working on a patient in the back, and used the lights and sirens to speed up his getaway.

The wild episode unfolded on Christmas Day when paramedics responded to a call at an Austin homeless shelter, KVUE-TV reported.

As they were working on the patient in the back, an unidentified man hopped behind the wheel and sped off with the crew and patient still on board, authorities said.

“Completely unexpected,” said Austin-Travis County EMS Capt. Rick Rutledge. “A surprise to everyone.”

The crew quickly strapped the patient in and was able to keep police updated throughout using their radios.

Eventually, the driver pulled into a housing complex and fled and has yet to be found. Officials say the man switched on the vehicle’s flashers and siren, but they aren’t sure if he knew the crew was in the back.

Rutledge noted that the back area of the ambulance is completely cut off from the driver’s compartment with no way of communicating between the two sections.

“There was never a conversation or an ability to question them, so we don’t really know what their motives were,” he said.