By early afternoon, firefighters said they had reached 50% containment, after the blaze had forced mandatory evacuations and ravaged a number of homes.
The evacuation orders were being lifted as of 6 p.m.
San Bernardino County firefighters first responded to the area of Highway 18 at Lower Waterman Canyon at about 1:38 a.m. as strong winds carried the flames amid extreme red flag conditions.
The Hillside Fire spread rapidly amid strong Santa Ana winds, reaching 200 acres by about 2:30 a.m., officials said.
Six homes were destroyed and 18 were damaged.
"You look up the hill and its barreling over the water tanks," said homeowner Eric Johnson. "The embers were flying. Everything was going south really quick."
Johnson knew how lucky he was that his residence escaped the flames, even as some of his neighbors suffered damage. He had lost a home to fire in Running Springs in 2007.
Dramatic photos pay tribute to firefighters on the front lines of California wildfires
By 1 p.m., the size estimate remained steady at 200 acres. Crews remained on-scene performing mop-up duties and looking for hotspots.
One firefighter was transported to a local hospital for smoke inhalation.
Evacuation orders were issued earlier as the fire threatened the North Park neighborhood. Mandatory evacuations were declared in areas for all homes north of 50th Street, west of Highway 18, and east of Mayfield Avenue.
Highway 18 had been shut down from Waterman Canyon and 40th Street to the SR-18/SR-138 split .
Officials said the highway was reopening in both directions as of 1:30 p.m.
An evacuation center was set up at Pacific High School at 1020 Pacific Street. Approximately 490 homes and 1,300 people were under evacuation due to the fire, according to officials.
Small animals can be taken to the San Bernardino City Animal Shelter at 333 Chandler Place.
Hillside Fire destroys homes in San Bernardino
It was not immediately known how many structures were threatened or destroyed, but multiple homes were seen damaged. Homes in the North Park community were seen surrounded by intense flames.
Cal State San Bernardino was closed as it remained without power, excluding its Palm Desert campus. Officials with the San Bernardino City Unified School District said its schools remain open and are monitoring the fire.
Structure defense was being put in place as strike teams were requested. Approximately 350 personnel were at the scene, according to the San Bernardino National Forest.
San Bernardino County fire officials discuss Hillside Fire at news conference
Shortly after 10 a.m., the Fire Department said investigators had determined the area of the blaze's origin, adding that the official cause was still undetermined.
"There are NO power lines near the area of origin," the agency said on Twitter.
Officials said high winds continued moving through the area with gusts reaching up to 60 mph.
Southern California is in the midst of increased fire risk as strong winds continue in the region through at least Thursday evening.
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