Some evacuees from a large fire in northeast Portland have been given the OK to return home.

Officials asked up to 4,000 residents to evacuate Monday because of unhealthy air. The fire in an auto-salvage yard burned cars and tires, sending heavy black smoke into the sky.

Multnomah County officials cut the size of the evacuation zone early Tuesday, but it’s still in effect for the four blocks closest to the scrap yard. More than 100 evacuees stayed in a shelter overnight.

The fire began Monday morning and burned all day. It spread to a duplex and an apartment building, destroying both.

No people were injured, but many pets died.

The cause of the fire is still under investigation.