An evacuation order is in effect for about 300 homes in Arcadia and Sierra Madre.By CBSLA Staff

MONROVIA (CBSLA) – A massive wildfire burning in the Angeles National Forest north of Monrovia came within 500 feet of the Mount Wilson Observatory, fire officials said Tuesday.

Several radio and TV communication towers are positioned near the Observatory and sit directly in the path of the Bobcat Fire. Twelve L.A. County Fire Department companies have been stationed around it for protection.

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U.S. Forest Service crews were also positioned near the site Tuesday afternoon.

The fire grew considerably Tuesday morning as firefighters worked tirelessly to protect both the Mount Wilson Observatory in the Angeles National Forest and the San Gabriel foothill communities which remain under threat.

The Bobcat Fire had burned at least 41,231 acres as of 10 p.m. Tuesday. Containment dropped from 6% to 3% between Monday and Tuesday. No homes have been destroyed.

Smoke rises behind the Mount Wilson Observatory as the Bobcat Fire burns in the Angeles National Forest on Sept. 14, 2020 near Pasadena, Calif. (Getty Images)

“We’re really lucky that we don’t have Santa Ana conditions right now,” said retired firefighter Glenn Faulk, who lives in Monrovia. “If we did, all bets would be off.”

The reduction in containment was due to the exponential growth in the size of the fire, coupled with crews being unable to increase containment lines, the U.S. Forest Service reported.

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Faulk said, after working for nearly 30 years in the same steep terrain, he understands the current struggle.

“It’s really hard to defend when the fire’s blowing the flames right back at your face,” he said, adding that while the flames burn downhill slowly, they burn uphill in an instant.

An evacuation order is in effect for about 300 homes in Arcadia and Sierra Madre. Arcadia Fire Department told CBSLA it has so far successfully kept the blaze out of its neighborhoods.

Sept. 14, 2020. (U.S. Forest Service)

The Bobcat Fire broke out a little after noon on Sept. 6 amid triple-digit temperatures near the Cogswell Dam and the West Fork Day Use area. The fire is churning through thick vegetation and dry brush in steep terrain, some of which has not burned in more 60 years.

The cause is under investigation.

An evacuation order in portions of Arcadia and Sierra Madre applies to all residents north of Elkins Avenue and east of Santa Anita Avenue.

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Evacuation warnings remain in place for Monrovia, Bradbury, Sierra Madre, Altadena, Duarte and Pasadena.