Crews built containment lines Sunday around a wind-driven wildfire that scorched nearly 4 square miles of dry brush and forced people to evacuate part of a Southern California military base.

The blaze at the Marine Corps' Camp Pendleton was 20 percent contained as the fire danger subsided with calmer winds late Sunday.

The fire broke out Saturday amid hot, dry and blustery conditions throughout the region. It quickly prompted the evacuation of 230 residents from a housing unit near Lake O'Neil and caused minor damage to four buildings, base officials said. Photos posted on Camp Pendleton's Facebook page showed a few charred vehicles.

The evacuees spent the night elsewhere on the 195-square-mile coastal base in northern San Diego County and were allowed to return home Sunday evening.

Naval Hospital Camp Pendleton was not threatened by the fire, but a power outage prompted officials to evacuate about 30 patients to other hospitals in the area and stop accepting new patients. Service at the hospital was restored by late Saturday, and the transferred patients were brought back to the hospital Sunday.

Nearly 340 firefighters were at the scene. The fire's cause was under investigation.

About 40 miles to the north, a fire sparked in a mulch pile at a nursery near Santiago Canyon in Orange County prompted the evacuation of 23 residents. The fire was not threatening homes and an RV park in the area, but residents were evacuated because of heavy smoke and in case a spot fire is ignited, said Orange County Fire Authority Capt. Steve Concialdi.

The blaze, reported late Sunday morning, burned an outbuilding and quickly charred about 30 acres of surrounding wild vegetation. One firefighter suffered a minor injury.

"Mulch piles get hot, and when a fire breaks out it's hard to douse the flames," Concialdi said. "We're going to be here all night into tomorrow to make sure it doesn't spread."

The powerful Santa Ana winds that kicked up late Thursday subsided by Sunday evening. The fierce winds triggered a red flag warning of extreme fire danger from the National Weather Service, which called the situation the region's "most significant fire weather threat in the past five years."

A peak wind gust of 90 mph was recorded Saturday morning at Laguna Peak in Ventura County.

Wind gusts of 65 mph were reported near the area of a small fire Saturday near a key freeway interchange in northern Los Angeles County. The effort to put out the fire brought traffic to a standstill for about 90 minutes.

The driver of a big rig that went off U.S. 101 in Oxnard and crashed into a car dealership said wind was a factor in the crash, police in the Ventura County city said. The crash caused a fire that spread to vehicles in the lot.

Forecasters said the summer-like weather is expected to shift by midweek, when a storm system could bring much cooler temperatures, rain and possible mountain snow to southwest California.