Firefighters were battling eight separate vegetation fires near Marsh Creek and Morgan Territory roads Saturday, prompting temporary evacuations and shelter-in-place orders near Clayton in Contra Costa County.

By Sunday morning, the Marsh Complex fires had burned about 655 acres and were 85 percent contained. At least six Cal Fire aircraft were providing air support, officials said.

One firefighter with Cal Fire was taken to a local hospital with a heat-related illness, said Jonathan Cox, a division chief with Cal Fire. The firefighter’s condition is unknown. No other injuries were reported.

Cox said low-wind conditions assisted more than 400 firefighters in “gaining the upper hand” on three of the larger fires blazing in the complex.

Cal Fire officials said they would remain on the scene overnight and into Sunday.

Residents of the Clayton Palms Community, which was temporarily evacuated, were shocked by the early-morning fires.

Natalie Funke was sleeping in bed shortly after 3 a.m. when the blaring of a car horn seeped into her dreams as a neighbor sped through the community, warning that fires were blazing nearby.

Her husband, Brandon, was on the front porch talking with neighbors as the orange-red cast from one of the eight fires peeked over a towering hill. It wasn’t until Funke heard the rolling sound of fire truck sirens in the distance that she started to panic.

“You couldn’t feel the heat, but the smoke was horrible,” Funke said. “We were not prepared because you never think this could happen to you.”

Funke grabbed underwear for her, Brandon, and their 11-year-old daughter, Kylee. They rounded up their two dogs, Paris and Spot. The couple slipped on flip-flops and Kylee, who was barefoot, cradled one of the dogs in her arms, and brought a teddy bear from her grandmother.

“I’m so proud of how she kept it together,” Funke said, her voice breaking. “She grabbed what was important to her and she got out.”

As the sun rose Saturday, a long line of flames was visible along ridgelines in the area.

Sheriff’s deputies went door to door in the community, telling residents to evacuate. Most piled into cars and fled, Funke said, but some residents chose to stay in their homes.

“We are just incredibly grateful to Cal Fire and first responders who risked their lives to save people that they didn’t even know,” Funke said. “And to my neighbor who took her time to go through the community in her car, she thought about everyone else. That was smart thinking on her part.”

Cal Fire Deputy Chief Mike Marcucci said Clayton Palms residents were allowed to return to their homes at around 6 a.m. Saturday. No further evacuations in the area are anticipated.

A shelter-in-place order was issued near Clayton. Officials asked residents to remain indoors with windows and doors closed. The order was lifted by Saturday night.

Cal Fire Assistant Chief Michael Borelli said the fire had not been growing much Saturday, since the morning weather conditions were “mild.” He was concerned that afternoon temperatures in the 90s could make firefighting more difficult. The heat-related injury to a firefighter was evidence of that.

The cause of the blazes was not immediately known.

The remote area is home to stables, small farms and a sheriff’s detention center, and is a popular cycling route. On social media, horse owners expressed concern.

“The fire is getting really close to my horse and they’ve closed the roads and I can’t get to her,” one horse owner wrote. “I’m flipping out.”

Steve Rubenstein and Lauren Hernández are San Francisco Chronicle staff writers. Email: srubenstein@sfchronicle.com and lauren.hernandez@sfchronicle.com