SAN DIEGO (CBS 8) – An ambulance erupted in flames in Pacific Beach while emergency crews were transporting an elderly patient to the hospital.

The entire event was recorded on cell phone video by witness Stephen Cornwell.

CBS News 8 was told that ambulance driver noticed smoke rising from the engine as they drove northbound on Interstate 5 with an elderly woman in the back of the ambulance.

The EMTs pulled over to the side of the road on Mission Bay Drive, north of Garnet Avenue, and rushed the patient to safety in the parking lot of the McDonald's across the street.

The ambulance is not operated by the city, but instead by AMR - a private ambulance company.

The cause of the fire is still under investigation. The two paramedics and patients are expected to recover from the episode.