Camp Pendleton Blaze Smothers I-5 for Hours : Fire: Freeway is closed 12 hours, and 7,000 acres are burned. The blaze is not expected to be controlled until today at the earliest.

A brush fire fanned by Santa Ana winds blackened 7,000 acres in and around Camp Pendleton on Wednesday, severing the Interstate 5 link between Orange County and San Diego, jamming surface streets and swaddling the San Onofre area in billowing smoke visible for more than 30 miles.

About 2 p.m., with the afternoon rush hour close at hand, the California Highway Patrol reopened a 20-mile stretch of freeway that had been closed in both directions for 12 hours and began escorting groups of 300 drivers through the smoke-filled and soot-coated stretch.

The escorts were suspended, and traffic was allowed to flow through unassisted shortly after 5 p.m. But as the flow of rush-hour vehicles continued its usual crawl in both directions after sundown, a red glow of fires was visible to the east, and firefighters kept a vigil along the side of the road, using flashlights to search for signs of embers.

Marine Corps officials said they do not expect the fire, which had burned 7,000 acres as of Wednesday afternoon, to be controlled until today, at the earliest.

“The wind is so erratic, it has literally gone in every different direction since we got here,” said Orange County Fire Battalion Chief Dan Runnestrand. “If it does, then all of this work is for nothing. We’re under control now, but that could change at any time.”

The freeway closure caused one of the biggest traffic delays in the area in recent history. Stranded motorists accustomed to zipping through the stretch between Los Angeles and San Diego grew impatient.

“I’ve been a trucker for six years, and this is the biggest mess I’ve ever been in,” groused independent truck driver Marino Gonzalez, 35.

The fire forced intermittent halts in passenger train service until midday. It triggered an alert at the San Onofre nuclear power plant, forced temporary evacuation of up to 300 residents from the Camp Pendleton military housing and singed a few buildings at the U.S. Border Patrol checkpoint, authorities said.

Smoke hitting the San Diego Gas & Electric Co.’s power lines around Camp Pendleton left more than 10,000 customers from Mission Viejo down through San Diego with electrical problems. Most experienced flickering lights; others had blackouts. But company officials said power was back to normal by about 1 p.m. as winds shifted the smoke away from the power lines.

The cause of the blaze, which broke out about 8 p.m. Tuesday in the the northern part of the base, about half a mile east of the busy freeway, remains under investigation.

By Wednesday, the inferno was in fact two separate fires, about 15 miles apart. The Rattlesnake Canyon blaze at the southern end of the base appeared to be under control after burning about 500 acres of brush.

More than 500 firefighters from Camp Pendleton, San Diego and Orange counties, as well as state and federal forestry firefighters, battled the blaze. They were reinforced by six planes, three helicopters and four bulldozers. Officials said one county firefighter suffered a knee injury on the fire lines.

Firefighters were frustrated by 35-m.p.h. erratic winds that gusted up to 45 m.p.h. to fan the flames.

“The biggest problem is the wind,” said Capt. Rose-Ann Sgrignoli, a media operations officer for the base.

A six-mile stretch on both sides of Interstate 5 from the nuclear power plant to the Las Pulgas Road exit was ravaged where flames had jumped across the lanes, burning the center divider and consuming dry scrub brush all the way to the ocean. Several structures inside San Onofre State Park had also burned.

The fire burned about six hours before becoming enough of a hazard that CHP officers closed the southbound lanes of Interstate 5, the main artery between San Diego and Los Angeles, about 1:40 a.m. Initially it was closed at Basilone Road, but five hours later farther north at Camino las Ramblas. The northbound lanes were shut down after 3:30 a.m.

San Diego-bound motorists were instructed to turn around and take Interstate 5 northbound to the Costa Mesa Freeway, then pick up the Riverside Freeway to Interstate 15 into San Diego, a detour that was taking most motorists about three hours, authorities said.

Some motorists who made it across the base late Tuesday--before the interstate was closed--were treated to the ride of their lives.

“The flames were burning right in the middle median strip at San Onofre,” Tori Surrey of Escondido said of her 11 p.m. trip across the base from Los Angeles to San Diego.

“You could see the flames in the distance as you came south. We couldn’t believe the freeway hadn’t been closed off. I just told my husband, ‘David, please drive fast.’ I’ve never seen a fire like this.”

The fire was traveling south parallel to Interstate 5, authorities said. Even after the freeway itself was no longer in danger, the CHP kept the road closed because heavy smoke cut visibility to almost zero.

At midmorning, Camp Pendleton opened its interior roads to detoured cars heading north through the base. Southbound traffic into San Diego County, however, was directed inland to Interstate 15, officials said.

As a result, the southern end of San Clemente became a parking lot of frustrated truckers and motorists whose passage into San Diego came to a grinding halt.

Hundreds were directed off the freeway at Camino las Ramblas in San Clemente, near Doheny State Beach Park, and they weaved onto four-lane El Camino Real, a frontage road along the east side of the interstate.

There, traffic was backed up--and literally stopped--for two miles as motorists were confronted by thick plumes of orange-brown smoke. Finally, shortly after noon, the CHP began letting the big rigs use the inland roads through Camp Pendleton.

When visibility improved somewhat by early afternoon, the CHP began to escort groups of motorists through the haze, keeping the vehicles bunched tightly together and traveling no faster than 35 m.p.h., fearing that unescorted motorists traveling fast would be forced to slam on their brakes in smog-clogged stretches, creating accidents.

By Wednesday afternoon Caltrans had posted an electronic sign on southbound the San Diego Freeway between Fairview and Bristol streets--about 20 miles north of the shut-down section--advising motorists of half-hour delays and CHP escorts from San Clemente because of the fire.

The blaze prompted officials at the San Onofre nuclear plant to declare an “unusual event,” the lowest-stage alert, just after midnight Tuesday when flames jumped the freeway and came within a quarter-mile of the plant. Southern California Edison officials notified local agencies, and the plant’s firefighting crew assisted Marine Corps firefighters, but the plant was not in danger, said Edison spokesman Dave Barron.

The power plant emergency was called off at 2:30 p.m., when the flames moved six miles south of the plant, officials said.

Train travelers did not have it much easier.

Amtrak spokesman Patrick Jeffrey said the track for the Los Angeles-San Diego train was threatened by fire and shut down twice. It was first shut down at 4:08 a.m. Wednesday and reopened at 8:10 a.m., but winds blew the flames back and the track was closed again at 10:25 a.m. and reopened at 1 p.m. During those shutdowns, the northbound train from San Diego was turned around at Oceanside, and the southbound train from Los Angeles was turned around at San Juan Capistrano. Buses were provided to transport passengers past the closed-off section, Jeffrey said.

“It’s been like the ‘Perils of Pauline’ here,” said Cliff Black, an Amtrak spokesman in Washington.

Only two trains--one northbound and one southbound--made it across the base during the seven hours after the tracks were originally closed, forcing would-be passengers to endure delays of up to eight hours, Black said.

Staff writers John M. Glionna and Sonni Efron and correspondents Wendy Paulson, Len Hall and Shannon Sands contributed to this story.