More than 17,000 people were under evacuation orders in southern California on Tuesday as a wildfire threatened suburban homes.

The wind-driven Sandy fire was reported on Monday in the hills above Simi Valley, about 30 miles (48km) north-west of Los Angeles.

By Tuesday morning, it had consumed more than 2 sq miles of dry brush and destroyed at least one home, according to the Ventura county fire department.

The flames were initially pushed by gusts that topped 30mph (48km/h), but firefighters were aided by calmer winds overnight, said a department spokesperson, Andrew Dowd.

“We’ve made a lot of progress against this fire with those improved weather conditions,” Dowd said. Crews hoped to make further progress before winds increased again, he said.

About 750 firefighters had been assigned to the fire by Tuesday, along with helicopters and air tankers, according to the Ventura County Star. The fire has destroyed at least one home.

The fire was 5% contained by midday on Tuesday. The cause is under investigation.

Evacuation orders and warnings were still in place for several neighborhoods in Simi valley, a city of more than 125,000 people.

Los Angeles officials are monitoring the fire, but expected firefighters in Ventura county to halt its progress.

“While the Sandy Fire is in Ventura County, the Los Angeles Fire Department continues to closely monitor the situation and has deployed resources on the ground – including strike teams, a hand crew, and helicopters – to assist local crews in firefighting efforts,” Los Angeles’ mayor, Karen Bass, said in a statement. “At this time, we do not expect the wildfire to reach the City of Los Angeles.”

To the south-east, two fires broke out midday Tuesday in Riverside county, prompting evacuation orders there. The Bain fire had grown to 250 acres by the afternoon, and injured at least four people, according to ABC 7 News.

The nearby Verona fire had burned 175 acres within two hours of starting. Both fires remained zero per cent contained by Tuesday afternoon.

Meanwhile, firefighters were battling a 23-sq-mile blaze on Santa Rosa Island, off the southern California coast – nearly one-third of the island’s surface area. The fire destroyed a cabin and an equipment shed and forced the evacuation of 11 National Park Service employees.

Santa Rosa, a popular destination for camping and hiking, is home to island foxes, spotted skunks and elephant seals. The island is home to six plants that grow there exclusively.

“Rare plants are among the remarkable ecological resources that Santa Rosa Island is known for,” Sierra Frisbie, a fire information officer, wrote in an email. “As part of the incident management team, Resource Advisors are assisting firefighters by providing guidance on how to protect these sensitive areas during operations when possible.”

The Santa Rosa fire appeared to start after a shipwrecked sailor shot off at least two flares in an attempt to catch the attention of passing boats. He was rescued without injury after passing the night on the island, according to the US Coast Guard. The National Park Service says it is still investigating the cause of the fire.