PALA MESA VILLAGE - A fiery, fatal crash early Monday became a hazardous materials problem with spilled bleach and ammonia, backing up traffic for miles and for hours on southbound Interstate 15 in North San Diego County.

A sport-utility vehicle slammed into the rear of a slower-moving semitrailer just before 12:30 a.m. in the freeway's right lane, about 13 miles north of Escondido, according to authorities.

They said the southbound lanes weren't flowing smoothly again at 35 mph or more until 12:09 p.m.

At one point, authorities said, traffic backed up about 11 miles from the crash site on southbound I-15, stretching as far north as the U.S. Border Patrol checkpoint in Riverside County.

The 2004 GMC Yukon wedged under the trailer and burst into flames, trapping the 52-year-old Bonsall driver in the wreckage half a mile south of Highway 76 at the start of a grade, officials said. He died at the scene.

Heat from the fire caused plastic bottles containing ammonia and bleach to melt, and a small amount of the liquids leaked hours later from the trailer when an attempt was made to move it after 7 a.m., officials said.

The lanes had to be shut down again for the hazardous materials cleanup, and they weren't reopened again until 11:44 a.m., said Hayden Manning, spokesman for the California Department of Transportation.

Fire Division Chief Sid Morel of the North County Fire Protection District said that immediately after the crash, the truck driver "told everyone that he just had paper goods, water and Gatorade, and that wasn't an issue at the time."

However, when the bleach and ammonia started leaking, everyone knew there was more in the trailer than what they had been told, said Officer Jim Bettencourt of the Highway Patrol.

"We really didn't know what the product was, so that kicked it into a haz-mat (situation)," Morel said.

He said no one was hurt by the leaking liquid, and a hazardous materials team was called to clean up the spill.

The semitrailer was still at the roadside, waiting to be cleaned out, when firefighters left the scene, Morel said.

Officer Tom Kerns said the Yukon was traveling at an unknown "high rate of speed" when it rear-ended the 2005 Freightliner truck, which was traveling at 45 mph on the rural section of freeway.

It wasn't known why the Yukon driver didn't stop or swerve in that area of hills and curves, Kerns said.

"The driver of the big rig pulled over onto the road shoulder, dragging the Yukon with it," he said.

The blazing crash blocked the freeway's outer lane, causing other drivers to stop or slow to see the fire. Another lane was shut down for the investigation and removal of the wreckage.

Kerns said the driver of the Smart & Final truck, 22-year-old Toney Allen Carroll of the Los Angeles area, wasn't hurt.

The name of the man who died was being withheld until his family was notified.

- Contact staff writer Jo Moreland at (760) 740-3524 or jmoreland@nctimes.com.