SAN DIEGO -- A Carlsbad couple and their 19-year-old grandson were killed Tuesday when the minivan they were in plowed into a stalled big rig on Interstate 5 in the Torrey Pines area, 10News reported.

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DEADLY CRASH IMAGES: Deadly Minivan, Big Rig Crash

The deadly chain of events began about 5:15 a.m., when the tractor-trailer broke down on the southbound 5, near Carmel Valley Road, and came to a stop in a traffic lane, the California Highway Patrol reported.

"It looks like he had driveline issues (with the big rig). There were large components of the driveline lying in the concrete which would indicate that he didn't have the ability to drive it," California Highway Patrol officer Steven Toth said.

Minutes later, a Honda Odyssey smashed into the back of the commercial vehicle. The motorist may have failed to see the disabled truck, despite its flashing hazard lights, CHP public affairs Officer Mark Gregg said.

Firefighters worked to remove the bodies from the van, which became wedged under the big rig.

Robert Jennings and his wife Marie died at the scene. Their 19-year-old grandson David Jennings, who had been riding in the back seat, was pronounced dead shortly after arrival at a hospital.

The trucker, an employee of a company called Transportes de Baja California, was uninjured.

"It's just one of those things where the vehicle experienced a mechanical breakdown and the driver was somewhat stuck. He turned his lights on, but trying to get out and do something when traffic is coming at him at such a high speed. It's just as dangerous for him to try and do something as well," Toth said.

The accident blocked several lanes of the freeway, causing traffic to back up for about 20 miles. The state Route 56 onramp to southbound I-5 was closed for several hours while the accident was cleared.

Officers say there was luggage in the back of the car and some airline tickets. It's likely they were on their way to Lindberg Field, apparently leaving on vacation.

"It was just gridlock. I wasn't moving, so I just pulled over and decided to save gas," a motorist told 10News.

"It took one hour and 45 minutes to go 28 miles," another motorist said.