LOS ANGELES >> A small twin-engine plane dropped out of the sky and exploded in flames on a busy freeway near a Southern California airport this morning, injuring the two people aboard but clipping only one passing vehicle, a fire official said.

The Cessna 310 aircraft crashed on Interstate 405, just short of a runway at John Wayne Airport in Costa Mesa around 9:30 a.m., said Ian Gregor, a spokesman for the Federal Aviation Administration.

The pilot declared an emergency shortly after taking off from the airport and was trying to return when the crash occurred, Gregor said.

The two people who were aboard the plane, a man and a woman in their 50s and 60, were alive when they were pulled from the fiery wreckage and were taken to a hospital with traumatic injuries, Orange County Fire Capt. Larry Kurtz told KCBS-TV.

The plane clipped a car as it crashed on the freeway, but the car’s driver suffered only a bruised elbow, Kurtz said.

“It’s very, very surprising,” he told the television station.

Video posted on social media showed the plane engulfed in flames and plumes of black smoke billowing into the sky. Traffic was backed up for miles on the major route between Los Angeles and San Diego as fire crews worked to extinguish the blaze.

Tina Foster had just left nearby John Wayne Airport when she heard a loud boom, which she initially thought was a car crash.

“By the time I got up to it the only thing I saw was the flames,” she said.

Foster posted a photo of smoke pouring out from behind the airport on Facebook to calm her friends’ fears after receiving texts asking if she were still alive, she said.

Another driver, Brian Gladish, said he was driving down the freeway when he saw a large cloud of smoke and flames.

“There was debris everywhere, the freeway was still on fire,” he said.

AP reporter Alina Hartounian contributed to this report from Phoenix.