A plane drops fire retardant as firefighters battle a blaze in El Portal, Calif., near Yosemite National Park on Tuesday, July 29, 2014. Firefighters in the state are also battling another wildfire in the Sierra Nevada foothills east of Sacramento. (AP Photo/Al Golub)

A plane drops fire retardant as firefighters battle a blaze in El Portal, Calif., near Yosemite National Park on Tuesday, July 29, 2014. Firefighters in the state are also battling another wildfire in the Sierra Nevada foothills east of Sacramento. (AP Photo/Al Golub)

YOSEMITE NATIONAL PARK, California — Firefighters brought a blaze that had spread in Yosemite National Park under control, and containment lines kept the wildfire from threatening some of the treasured sequoias that are among the largest and oldest living trees on Earth.

The flames spread about a half-mile (800 meters) Wednesday, park officials said in a statement, but it was brought under control.

The fire remained about 10 miles (16 kilometers) from Merced Grove, one of three Yosemite stands of giant sequoias. The towering trees grow only on the western slopes of the Sierra Nevada and can live longer than 3,000 years.

Flames could reach the grove if the fire makes a significant surge, park spokesman Scott Gediman said.

Low humidity was likely to lead to an active night for the fire into Thursday, and thunderstorms brought the threat of lightning, the park's statement said.

With the exception of some smoke in Yosemite valley, the park itself was largely unaffected by the fire and remained open, Gediman said.

The fire was threatening about 50 homes that remained under evacuation orders. It has destroyed a home and a duplex and burned through more than 6 square miles since it began on Saturday. It was 34 percent contained.

Fire crews also were battling a blaze in Sierra National Forest about 60 miles (96 kilometers) northeast of Fresno that grew substantially late Tuesday and had spread across nearly 9 square miles (23 sq. kilometers). It was threatening about 20 homes, though they were not under mandatory evacuation orders, said Anne Grandy, a spokeswoman for the park.

Several campgrounds and cabins were evacuated and closed, the U.S. Forest Service said in a statement.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.