SANTIAGO PEAK (CBSLA) – A new flare-up crossed containment lines of the arson-sparked Holy Fire Monday in the Cleveland National Forest and burned 150 acres.

The flare-up, which broke out at around 9:20 a.m. near Santiago Peak in Orange County, jumped containment lines and sparked a spot fire. It was 10 percent contained as of Tuesday morning, according to the U.S. Forest Service. It was threatening communication towers on Santiago Peak.

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Aug. 27, 2018. (CBS2)

Orange County Fire Authority Capt. Tony Bommarito said five air tankers and four helicopters were assigned to the fire, with the primary goal of protecting communication towers on the peak. He noted that no residential structures were being threatened.

About 300 personnel were battling the blaze. Jake Rodriguez, a USFS spokesperson, said the flames were spreading at a “slow to moderate” rate, and crews were focusing their attention on the western flank, “where there’s open vegetation.”

The 23,986-acre Holy Fire broke out in the Holy Jim Canyon area on Aug. 6 and then marched east into Riverside County towards Lake Elsinore. It was 94 percent contained as of Monday’s flare-up, with small spots continuing to smolder along the rim of the burn zone. Full containment was not expected until Sept. 2.

It destroyed 18 homes in Orange and Riverside counties and forced thousands of people to flee.

Forrest Gordon Clark, 51, was arrested on multiple arson charges in connection with the fire.

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Clark has a cabin in Holy Jim Canyon, and arson investigators allegedly uncovered evidence indicating the fire was ignited in the immediate vicinity of his property, according to OCFA.

A volunteer fireman, Mike Milligan, who has a cabin near Clark’s, claimed Clark has had a long-running feud with a neighbor and other cabin owners. In the days prior to the fire, Clark ran through the area screaming and sent Milligan a message warning that “this place will burn,” he said.

Clark is being held in lieu of $1 million bail and is undergoing a court-ordered evaluation for mental illness.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)