Crews finish digging containment lines around Lilac Fire

BONSALL, Calif. — Fewer than 140 firefighters remained in San Diego’s North County Thursday to finish digging containment lines around the Lilac Fire, which burned 4,100 acres and destroyed 157 structures between Fallbrook and Oceanside near Camp Pendleton, authorities said.

The fire was 97 percent contained as of 7 Thursday morning — one week since the first flames broke out for unknown reasons west of Interstate 15 and north of Lilac Road in Pala Mesa amid gusty, arid Santa Ana winds.

In total, 1,659 firefighters and other personnel helped battle the blaze at one point or another, though that number was down to 779 as of Wednesday morning as crews finished digging containment lines to isolate the burn area in case of hotspot flare-ups.

The number of firefighters still assigned to the fire was just 137 Thursday morning.

Photos: Lilac Fire devastation

Responsibility for creating the perimeter around the smoldering burn zone was transferred Wednesday to Cal Fire San Diego units. Prior to Wednesday, all decisions were being made by a joint command team from Cal Fire, the North County Fire District and the Vista and Oceanside fire departments.

Officials expect to have the blackened burn zone fully contained a week from Thursday.

The Lilac Fire destroyed 157 structures — many of them dwellings in the Rancho Monserate Country Club mobile home park in Fallbrook — and damaged 64 more. No human deaths were reported, but at least 46 horses died, many of them stabled at the San Luis Rey Downs Training Center in Bonsall.

As crews wind down their work containing the Lilac Fire, the same type of Santa Ana winds that drove the blaze are expected to again sweep through parts of San Diego, though they’ll be weaker than they were last week. Still, the National Weather Service issued a red flag warning that went into effect at 4 a.m. Thursday for San Diego County’s inland valleys and mountains. It’s set to expire at 10 a.m. Friday.

The red flag warning signifies critical fire weather conditions “are either occurring now, or will shortly,” the NWS said. Those conditions include “strong winds, low relative humidity and warm temperatures (that) can contribute to extreme fire behavior.”

With humidity levels hovering near single digits, the NWS warned that outdoor burning should be avoided and “any fires that develop will likely spread rapidly and be difficult to contain.”

The Santa Ana winds that prompted Thursday’s red flag warning are expected to die down by Friday morning before strengthening again Saturday night into Sunday. Locally, fire agencies are bracing and preparing for any new fires, while in Ventura and Santa Barbara counties, fire crews are continuing to battle the massive Thomas Fire.

That blaze, which broke out 11 days ago and is still only 30 percent contained, has now grown to the fourth largest in California’s history at more than 242,000 acres burned. The 2003 Cedar Fire in San Diego County still holds the record as the state’s largest wildfire at 273,246 acres, while the 2007 Witch Fire and 1970 Laguna Fire, both in San Diego County, are also among the 10 largest in California history.