Thousands of acres in Malibu remain ablaze as firefighters work to make progress to contain the Franklin Fire and lift some evacuations in the area, officials said Thursday.

A once fast-moving blaze that scorched more than 4,000 acres and destroyed nine structures is now 20% contained as crews tackled areas still smoldering, Cal Fire Assistant Chief Dusty Martin said in a briefing. The cause of the fire remains under investigation, Martin added, as teams sifted through about 25% of the debris.

“We have to allow them space to do the investigation and then they will come back to report to us,” said Martin who gave no timetable when the officials will meet with investigators.

Officials also said some Malibu residents will be allowed back to their homes as some evacuation orders are expected to be lifted as soon as Thursday evening. The orders will lifted primarily for those residents who live east and west on the Pacific Coast Highway.

Los Angeles County Sheriff’s Department Capt. Jennifer Seetoo and County Supervisor Lindsey Horvath urged residents to be patient and asked that they listen to the authorities about re-entering their communities.

“For those returning back home today, we welcome you,” Horvath said. “For those who are not returning yet, every effort is being made to return you back home.”

The updates come as previous red flag warnings have expired. Crew could also get some relief as a band of rain showers and cooler air move through Southern California, officials said.

Temperatures could reach as high as the mid-60s, Joe Sirard, a meteorologist with the National Weather Service in Los Angeles, told USA TODAY.

“But there are some westerly and northwesterly winds also in the forecast, which might not be good for the wildfire,” Sirard said Thursday. “It will moisten up a tiny bit, but the winds could be problematic in fighting any leftover hotspots.”

Meanwhile, evacuation orders remain in effect for some Malibu residents, and local schools were closed Thursday, officials said Thursday afternoon. Martin said late Wednesday that it probably would take a “number of days” to contain the fire because of the steep and inaccessible terrain in the Malibu Canyon area.

The fire was discovered late Monday, fueled by low humidity and strong Santa Ana winds. As the winds dropped off Wednesday, the National Weather Service in Los Angeles ended its red flag warnings but said that elevated to brief critical conditions would linger into Thursday for breezy areas such as southwest Santa Barbara County and the San Gabriel Mountains.

“Firefighters are making steady progress as relative humidity is expected to increase overnight, and weak northeasterly winds will persist into the evening,” according to a Cal Fire update from early Thursday.

Nearly 2,000 fire personnel have been assigned to the blaze, including multiple air tankers “that are flying fire suppression missions as conditions allow,” according to Cal Fire.

Flames licked the windows of the library on Pepperdine University’s campus Monday night where Religion and Philosophy Divisional Dean Dyron Daughrity was sheltering in place with roughly half the people still on campus.

It was Daughrity’s third wildfire in the 18 years since he started at Pepperdine, where he lives with his family on campus.

The sight of the flames right at Payson Library’s windows was “dramatic,” Daughrity said. The smell of smoke filled the air even indoors, and those sheltering stayed awake through most of the night. Though surrounded by at times frantic students, Daughrity said he had full confidence the firefighters would keep them safe.

“If you haven’t been through it before, it’s very scary, but if you have been through it before, you realize that these firefighters, they always come through,” Daughrity told USA TODAY on Thursday.

Come morning, they were allowed to return to their homes, only to be ordered back to the library again the next night as fire sprang up close to the other side of campus on Tuesday. The campus cafeteria has been feeding sheltered students, staff, and firefighters alike. As a group of firefighters walked in Wednesday evening, the cafeteria erupted in applause.

“Those men and women, their blackened faces and boots and all their equipment wearing blackened suits and everything,” he said. “You couldn’t find a dry eye in the place.”

As the strong winds fueling the fire began to subside and containment grew on the last day, most of the danger passed, the professor added. Smoke still fills the air, and “all around us the fire still burns,” but the campus itself remains mostly unscathed, Daughrity said.