A pair of wildfires broke out in southern California on Friday, marking the region’s first significant burns in a spring that has seen a major heatwave.

The fires started in windy conditions that have caused them to spread quickly. The National Weather Service issued a wind advisory for parts of southern California through midday Friday, warning of gusts up to 50mph.

Alex Izaguirre, a spokesperson for the Cal Fire Riverside County, said the wind is “spreading the smoke”, prompting concerned calls from residents in neighboring cities who saw and smelled the smoke.

The Springs fire in Riverside county has grown to 3,500 acres, prompting local authorities to issue several evacuation orders. The fire is concentrated in an area mostly north and east of Lake Perris, burning portions of the surrounding state recreation area, according to CalFire.

As the fire edged into Moreno Valley, a city of roughly 200,000, fire crews moved into place to protect the structures in the path of the blaze.

The cause of the Springs fire, which broke out at 11am, remains unclear.

Two helicopters, 36 fire trucks and some 260 personnel have been assigned to fight the fire.

The fire was 5% contained by Friday evening.

A second, smaller fire also broke out in Los Angeles county. The 260-acre Crown fire was 25% contained by Friday afternoon. The blaze has also prompted several evacuation orders in and around the unincorporated community of Acton.

Associated Press contributed reporting