Four wildfires broke out in southern California's Riverside County over the weekend amid sweltering temperatures, with much of the state under excessive heat warnings Sunday.

The largest of the blazes -- the Rabbit Fire -- had burned 7,600 acres by Sunday and is 10% contained after it ignited Friday afternoon, according to the California Department of Forestry and Fire Protection.

Cal Fire authorities reported a vegetation fire Friday in the community of Lakeview. The Rabbit Fire was first reported as 20 acres and burning with a rapid rate of spread. Cal Fire investigators are still looking into what caused it.

An incident update Sunday said at least 152 structures are threatened by the Rabbit Fire. Authorities said in the update they expect the blaze to be fully contained by Wednesday.

Firefighters made progress on Sunday and downgraded part of the evacuation order in place for the Rabbit Fire to an evacuation warning for several areas, Cal Fire tweeted.

Firefighters were also working to contain the much-smaller Reche, Highland and Gavilan fires that started in Riverside County on Friday and Saturday.

Evacuation orders for the Reche and Highland fires were lifted Sunday, according to an update from Cal Fire and the Riverside County Fire Department.

The Reche Fire has burned through more than 435 acres and is 60% contained, while the Highland fire has burned through 105 acres and is 70% contained as of Sunday afternoon.

"Those fires are pretty much wrapping up," Cal Fire Riverside County Fire Department Information Officer Captain Richard Cordova said Saturday.

Cordova added that containment lines for the two wildfires were improving.

The Gavilan fire, located in the unincorporated Perris area of Riverside County, has burned 250 acres and is 50% contained. Evacuation warnings for that fire remain in place, authorities said.

When asked how the high temperatures impact the fires and firefighters, Cordova said, "Obviously (it) has a big impact. That is what obviously causes our wildland fires here in California with the extreme heat plus the dry vegetation that is still out there from the drought. We are expecting heavy fuel loads out there for our firefighters."

Over 3,030 wildfires have burned more than 10,400 acres across California so far in 2023, according to Cal Fire.