An 83-year-old man was arrested after he signed himself out of a hospital and then stole an ambulance that had keys in the ignition early Tuesday, Nassau Police said.

According to police, Donald Winkler, of Potter Avenue in North Merrick, was an admitted patient at Nassau University Medical Center in East Meadow for an illness when he became upset with his care and signed himself out of the hospital around 1 a.m., police said.

Upon walking out of the emergency room doors and into the parking lot, Winkler observed and entered a Nassau County Police ambulance with the keys in the ignition and drove it away, police said.