SISTERS, Ore. (AP) — A fast-moving new wildfire is threatening about 100 vacation homes in central Oregon.

Central Oregon Interagency Dispatch Center spokeswoman Lisa Clark said the Geneva 12 wildfire had burned across about 1,600 acres or 2 ½ square miles of juniper and sagebrush by Monday night. She said it was reported earlier Monday and likely caused by Sunday lightning strikes. The wildfire is burning about 15 miles northeast of Sisters.

Clark says most of the threatened homes were vacant when authorities advised that residents should leave. Fire crews were focusing on that area.

Three air tankers and two helicopters helped about 140 firefighters battle the blaze Monday. Clark says fire crews planned to work through the night and hoped to make progress in cooler overnight temperatures.

Hundreds of weekend lightning strikes in central Oregon started a number of small fires.