(Reuters) -A county sheriff in Oregon ordered people living on the outskirts of the city of Salem to evacuate on Wednesday due to the imminent threat from a wildfire, as emergency services used aircraft to try to douse the blaze.

"GO NOW - Evacuate immediately!" the Marion County Sheriff posted on the social media site X. "Leave without delay. It is unsafe to stay and threatens the safety of you, your family."

Deputies were going door to door to warn people of the fire, the sheriff's department said.

The Oregon State Fire Marshall was helping fight the fire by mobilizing fixed-wing tankers, an air attack platform and a helicopter, it said on X.

The fire had burned at least 10 acres (4 hectares), the Statesman Journal reported, citing the state fire marhsal.

Salem is a city 180,000 people about 50 miles (80 km) south of Portland in the northwestern U.S. state of Oregon.

The fire was south of the city limits, near the interface between densely populated areas and green space.

(Reporting by Daniel Trotta; Editing by Simon Cameron-Moore)