SANTA MARIA, Calif. (AP) — Rising temperatures on Wednesday posed new challenges for firefighters who have made incremental progress against a massive wildfire in central California that has injured four people as it has become the biggest blaze in the state so far this year.

Gifford started along Highway 166 east of Santa Maria, adjacent to the footprint of the year’s previous biggest fire: Madre, which last month burned 80,779 acres in the Carrizo Plain area. Evacuation orders for Gifford covered almost 600 square miles, and Highway 166 was closed between Highway 101 and New Cuyama.

Temporary evacuation sites were established at Benjamin Foxen Elementary School in Santa Maria and the Cuyama Valley Family Resource Center in New Cuyama, Cal Fire said. The agency also reported that Highway 166 was closed between Highway 101 and New Cuyama.