Fireworks caused a 3,200-acre brush fire in the hills south of Redlands on Saturday that forced mandatory evacuations, rained down ash on nearby communities and sent up a plume of smoke that could be seen as far away as Riverside and the Big Bear area, fire officials said Saturday night.

The fire was 10 percent contained just before 10 p.m. Saturday.

An 8 p.m. tweet from Cal Fire said investigators had determined that fireworks had caused the blaze.

All fireworks are illegal in Riverside County, according to the Sheriff’s Department. Those caught with illegal fireworks are subject to fines, citation and/or arrest, the department says.

The Redlands-area blaze, dubbed the Palmer fire, prompted mandatory evacuations about 3:30 p.m. Saturday. About 100 homes were evacuated, according to the Riverside County Sheriff’s Department.

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Mandatory evacuations were ordered for Live Oak Canyon Road between San Timoteo Canyon Road and the 10 Freeway. There is also a hard closure of Redlands Boulevard south of San Timoteo Canyon Road, according to Cal Fire.

An evacuation center has been set up at Redlands Community Center, 111 W. Lugonia Ave.

Small animal evacuees can be taken to Redlands Animal Shelter, 504 N. Kansas St., Redlands officials said on Twitter. Large animals could be taken to the Yucaipa Equestrian Center. Several residents could be seen fleeing in horse trailers.

Redlands police also issued an advisory for residents along Outer Highway 10 between Live Oak Canyon Road and Alta Vista, as well as along Alta Vista to Sunset Drive to Helen Court. Those residents should be prepared to evacuate if the Palmer Fire jumps Live Oak Canyon Road, the city Fire Department said on Facebook.

Some residents, though, didn’t leave; instead, they stayed in their air conditioned pickup truck parked at the edge of their property near Live Oak Canyon Road.

“We have been through fires two times before this,” said Jim Bergendale, 77, adding: “We learned that if you leave they won’t let you back in.”

Jim and his wife Frances have lived on their 10-acre property for 20 years.

“The firefighters did an amazing job protecting houses,” Frances Bergendale said.

“I can’t believe how low those big planes fly,” Jim Bergendale.

Jim understood the need to move horses into less smoky areas – both for their mental health, as well as their physical health.

“Smoke really stresses horses,” said Cindy Jacobson, a Calimesa resident who brought an empty horse trailer to the fire area. “I’m here to move two horses to my place if anybody wants me to,” she said.

There were just two people at the Red Cross shelter set up for Palmer fire refugees at about 8 p.m. Saturday.

Concerns about smoke drove Robert Beck, 87, and his wife, Sally Beck, to the shelter.

“I’m very sensitive to smoke,” Sally Beck said.

An inmate brush crew marches along San Timoteo Canyon Road toward Live Oak Canyon Road with their head lamps on after battling the Palmer Fire in the background on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

A battalion chief checks out a flare up of the Palmer Fire as it burns into the night along San Timoteo Canyon Road near Live Oak Canyon Road in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

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The Palmer Fire burns into the night along San Timoteo Canyon Road near Live Oak Canyon Road in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

The Palmer Fire burns into the night along San Timoteo Canyon Road near Live Oak Canyon Road in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

Firefighters battle the Palmer fire, which blaze began about 1:30 p.m. at San Timoteo Canyon Road and Fisherman’s Retreat south of Redlands. (Photo courtesy of Cal Fire/Riverside County Fire Department)



A water-dropping helicopter is silhouetted against the sky as it fights the Palmer fire along San Timoteo Canyon Road in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

Bryan Ickes rescues miniature horse from the area of the Palmer fire, which began about 1:30 p.m. at San Timoteo Canyon Road and Fisherman’s Retreat south of Redlands. Mandatory evacuations were ordered. (Photo by Jim Steinberg, The Press-Enterprise/SCNG)

The Palmer Fire burns along San Timoteo Canyon Road near Redlands Boulevard in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

Residents record the Palmer Fire as it burns along San Timoteo Canyon Road near Live Oak Canyon Road in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

A battalion chief checks out a flare up of the Palmer Fire as it burns into the night along San Timoteo Canyon Road near Live Oak Canyon Road in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)



The Palmer fire that began about 1:30 p.m. at San Timoteo Canyon Road and Fisherman’s Retreat south of Redlands. (Photo courtesy of Cal Fire/Riverside County Fire Department)

The Palmer fire that began about 1:30 p.m. at San Timoteo Canyon Road and Fisherman’s Retreat south of Redlands. (Photo by Jim Steinberg, The Press-Enterprise/SCNG)

A tanker makes a retardant dump on a structure close to the Palmer Fire along San Timoteo Canyon Road in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

The Palmer fire that began about 1:30 p.m. at San Timoteo Canyon Road and Fisherman’s Retreat south of Redlands. (Photo by Joe Nelson, The Press-Enterprise/SCNG)

A DC-10 firefighting plane is silhouetted against the sky as the Palmer Fire burns along San Timoteo Canyon Road on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)



Firefighters work in the thick smoke of the Palmer Fire along San Timoteo Canyon Road in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

Heavy plumes of smoke from fill the sky as the Palmer Fire burns near a ranch home on the north side of San Timoteo Canyon Road in Redlands on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

Cattle graze on the grass the Palmer Fire did not burn at Eastside Ranch on San Timoteo Canyon Road as fire trucks work in the background on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

A resident evacuates as the flames from the Palmer fire near her home in the Redlands area on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)

A water dropping helicopter flies under the moon on its way back to make a drop on the Palmer Fire along San Timoteo Canyon Road on Saturday, Sept. 2, 2017. (Photo by Terry Pierson, The Press-Enterprise/SCNG)



The smoke plume from the Palmer fire, as seen from Cherry Valley Boulevard and the 10 Freeway in Beaumont. (Photo courtesy of Jarrod Loeffler)

The blaze began about 1:30 p.m. at San Timoteo Canyon Road and Fisherman’s Retreat west of Beaumont.

It initially headed east, but quickly moved west toward Live Oak Canyon Road, thanks to windy conditions, said Cal Fire’s Lucas Spelman.

It has jumped San Timoteo Canyon Road, he said.

“We do have firefighters down there fighting the fire aggressively,” Spelman said. “We were able to save some homes off Live Oak Road and we’re fighting to save the others.”

Spelman said it wasn’t yet clear whether any structures had burned.

“It definitely burned next to some structures, but we won’t be able to check immediately, because all of our resources are focused on fighting the fire,” he said.

More than 400 firefighters, six air tankers, two bulldozers and four helicopters were assigned to the blaze.

Among the tankers to join the blaze is Cal Fire’s latest: a Boeing 747 Very Large Air Tanker.

The tanker was first used Wednesday, Aug. 30, at the Ponderosa Fire in Butte County in Northern California.

“It’s definitely going to help out,” Spelman said. “It’s just like any other tool we have: By itself it couldn’t put the fire out, but together with our other tools, it helps.”

The new tanker has a capacity of 19,600 gallons of retardant, but Cal Fire only allows it to carry 18,500 gallons. The tanker with the next-largest capacity, a DC-10, carries 11,600 gallons.

Video of the Palmer fire: