Firefighters gained ground Monday against a large wildfire and three smaller blazes in the torrid interior of Southern California.

The Rabbit Fire grew slightly overnight to more than 12 square miles but containment jumped to 35%, according to the Riverside County unit of the California Department of Forestry and Fire Protection.

The fire, which broke out Friday afternoon about 65 miles southeast of Los Angeles, remained a threat to more than 150 structures but none had been damaged, Cal Fire said. The cause is under investigation.

Excessive heat warnings remained in effect for the region, where three smaller fires were in significant stages of containment.

Meanwhile a fire ignited by lightning late last month in Yosemite National Park grew slightly to more than 1 square mile.

Smoke from the Pika Fire northwest of the granite landmark called North Dome has been degrading air quality in Yosemite Valley during overnight and morning hours before lifting during afternoons.

The ongoing heat wave continued to bring oppressive conditions to inland portions of southern and central California while much of the north was free of heat warnings.