(Reuters) - Fire officials said on Monday they had effectively stopped the uncontrolled spread of the largest wildfire in Los Angeles history, with a little help from cooler weather, but were still working to contain it.

Los Angeles Fire Chief Ralph Terrazas said crews had cleared brush away from 30 percent of the perimeter of a fire that started four days earlier and has consumed more than 7,000 acres (2,800 hectares). But he stressed that firefighters were still largely at the mercy of the weather.

“There’s really no active fire left,” Terrazas told reporters. “That can change, though, with the wind. Our goal today is to continue to increase our containment percentage.”

Scattered rains, lighter winds, lower temperatures and higher humidity have helped more than 1,000 firefighters in the air and on the ground battle the blaze in the rugged northern edge of the city. The wildfire claimed four houses and caused minor injuries among six firefighters.

The La Tuna Fire, named after the canyon area where it erupted on Friday, forced the evacuation of more than 700 homes, as steady winds helped it tear through thick brush that has not burned in decades and temperatures hovered around 100 degrees Fahrenheit (38 degrees Celsius).

Los Angeles Mayor Eric Garcetti said on Sunday afternoon that 90 percent of the 1,400 people evacuated from their homes had returned and nearly all would be back by the end of the day. Officials also reopened a stretch of the 210 freeway that had been closed for days.

Terrazas said there was much work to be done, but stressed that officials had already mapped out the remaining 70 percent of the fire’s perimeter that firefighters and bulldozers need to clear to keep it fully contained.

Slideshow ( 17 images )

“We know what we need to do now, we just have to do it,” he said.

Researchers believe the wildfire is the largest in terms of area in the city’s history, Terrazas said.

Los Angeles County, home to 10 million people and vast tracts of undeveloped mountainous land, has suffered much larger wildfires that have burned for weeks.

California Governor Jerry Brown on Sunday declared a state of emergency for the county, which will ease the path for state and federal help to fight the fire.

More than 400 miles (650 km) to the north, the so-called Ponderosa Fire has burned 4,000 acres, or 1,600 hectares, and destroyed 32 homes in Butte County since it started on Tuesday, prompting evacuation orders to residents of about 500 homes. The blaze was 64 percent contained on Sunday evening, up from 56 percent earlier in the day.