REDDING, Calif. (AP) — Officials in California are warning people celebrating the Fourth of July against illegal fireworks and untended campfires as firefighters battle blazes that have destroyed homes in the tinder-dry state where the threat of more wildfires is high.

The three largest fires are burning in the northern part of the state. The Salt Fire near Mount Shasta has destroyed more than 40 buildings, many of them homes.

Crews working in sweltering conditions have made some progress against the fires.

Forecasters say the holiday will bring more hot and dry weather, so caution is crucial.