A pilot and his passenger have miraculously survived after their small plane crash-landed on a busy California motorway and burst into flames.

Their twin-engine Cessna 310R took off from John Wayne Airport in Orange County shortly after 9am on Friday (30 June) before the plane's right engine blew as it was still gaining altitude.

The 62-year-old pilot turned the plane around and made a May Day call to air traffic control, but was forced to land on the I-405 freeway shortly after the early morning rush hour.

Somehow, after crashing into the central divider and shedding debris across the street, the plane only hit one car as dozens more swerved away. Plumes of smoke could then be seen filling the California sky.

"This could have been extraordinarily bad," Orange County Fire Captain Larry Kurtz told the Orange County Register.

"Anytime you have a plane that crashes onto a freeway, the potential for great loss of life or great injury always exists," he said. "It was extraordinary that all the patients we had were just patients of the aircraft."

Shortly after the crash, videos shared on social media showed the blood-covered pilot being dragged from the burning wreck by John Meffert, an off-duty fire captain, as the 55-year-old female passenger was able to stagger away herself.

Meffert said he saw the plane flying low before it came crashing down on the motorway and was immediately engulfed in flames. After a wing of the plane his hit car, he pulled over and went running toward the blaze.

"It was one of those things where you think, 'It can't be happening,'" Meffert told reporters. "I called my wife and I said, 'I'm going to be a little bit late.'"

The two passengers were taken to Orange County Global Medical Center in Santa Ana, where they are said to be in a stable condition.