A sudden medical crisis is suspected of causing a driver to lose control of his sedan and slide into an oncoming bus in Anaheim.

The driver of the car died and 14 of those aboard the bus were hospitalized, authorities said.

The crash took place about 11:13 a.m. Tuesday morning on South Harbor Boulevard, just north of Ball Road, according to the Anaheim Police Department.

The driver of the Toyota Avalon was taken to the hospital in critical condition, but did not survive, police said. He was described as 60 years old.

The Orange County Transportation Authority bus had just pulled away from a stop, and was moving less than 15 mph when the collision occurred, said Anaheim Police Sgt. Daron Wyatt. The injuries to the bus driver and his passengers were described by police as not serious.

The car was southbound on Harbor Boulevard approaching Ball Road, but instead of making the gentle bend to the right, it continued straight into oncoming lanes, starting to spin and slide sideways.

An employee outside a nearby restaurant heard the skidding, looked up and saw the smoke from the tires.

"He spun, spun, spun, then I heard what sounded like an explosion," Benjamin Purney said.

The skid marks appeared to extend some 100 feet from the center divide lane to the point of impact. After the collision, a fire erupted under the car's hood. The driver of an arriving shuttle bus for employees of Disneyland neabry saw and used the an extinguisher to put out the fire, Purney said.

Images from the scene showed the crumpled Toyota near the bus, which sustained heavy front-end damage. Debris, including scores of stickers that police believe came from the car, was strewn across the roadway.

Investigators found indications the car driver may have suffered a disabling health episode, but that has yet to be confirmed, Wyatt said. The coroner has yet to release his name.

Police intend to view video recorded by an on-bus camera as part of the investigation.

Both sides of Harbor Boulevard remained closed between Vermont Avenue and Ball Road until shortly before 4 p.m.

NBC4's Jamie Bankson contributed to this report.