Hollywood couple's Tesla Model S burns ‘out of the blue’ in video

The U.S. National Transportation Safety Board (NTSB) will send a technical specialist to observe a Tesla examination into the causes of a battery fire last Friday involving one of the electric automaker's Model S vehicles in California, the agency said on Monday.

A spokesman for the NTSB said that observing the examination into the fire in West Hollywood will "provide the agency with an opportunity to learn more about fires in all types of battery-powered vehicles."

The car belonged to British movie director Michael Morris and his wife, actress Mary McCormack, who posted video of the fire on Twitter. There was no accident, and the fire erupted "out of the blue," McCormack said.

"And thank god my three little girls weren't in the car with him," she wrote.

The safety board is investigating four Tesla  crashes since last year and looking at post-crash fire issues and the use of Autopilot.

Earlier this month, the NTSB issued a preliminary report saying the driver of a Tesla Model X car using Autopilot did not have his hands on the steering wheel in the six seconds before a fatal crash in California in March.

A spokeswoman for Tesla said in an email that the battery fire on Friday was "an extraordinarily unusual occurrence, and we are investigating the incident to find out what happened."

She wrote that the cabin of the Model S was unaffected by the fire, allowing Morris to exit the vehicle safely.

"While our customer had time to safely exit the car, we are working to understand the cause of the fire," she added.