Firefighting helicopters soared over Mount Wilson early Tuesday, dropping water on a brush fire that broke out below the peak's famed observatory.
The barrage of early morning water drops helped hold the fire to 30 acres in the San Gabriel Mountains northeast of Pasadena. It was 35 percent contained as of 10 p.m., according to the U.S. Forest Service.
The Chantry Flats area was evacuated as a precaution. Red Box and Mount Wilson roads were closed, but no structures were threatened.
It was not immediately clear how the fire started.
The observatory in Angeles National Forest features powerful telescopes and solar towers. The peak also has an array of TV and radio broadcast equipment.
"We're attacking it from the ground and the air to keep it from running uphill toward the infrastructure," said Nathan Judy, spokesman for Angeles National Forest.
The observatory was founded in 1904 by astronomer George Ellery Hale. In the early 1900s, it became home to the largest telescopes in the world. Edwin Hubble, who joined the Mount Wilson staff in 1919, was among the highly regarded astronomers who used the observatory's telescopes to expand our understanding of the universe.
The fire started after a weekend of high fire danger in California, where several brush fires continued to burn. As of Oct. 15, CAL FIRE reported more than 6,000 fires in California so far this year. Those fires scorched nearly 480,000 acres. During that same period last year, CAL FIRE reported 4,457 fires that burned 244,000 acres.
California's five-year average through mid-October is 4,373 fires and more than 201,300 acres of scorched land.
The state is coming off one of its wettest winters in years, which left hillsides covered in grass and other vegetation. That grass dried out during summer and turned into tinder, providing fuel for rapidly spreading fires often pushed by strong winds.
NBC4's Karla Rendon contributed to this report.