UPDATE: North Cascades Highway opens with no stops where wildfire is raging

A wildfire in northeastern Skagit County has seen “explosive” growth and has become a crown fire in remote timberland as firefighters worked Thursday to build containment lines and aircraft were dropping water.

Highway 20 over the North Cascades, which was closed earlier in the day, has opened with no stopping allowed from milepost 148 to 158, according to the Washington State Department of Transportation.

“Stay on the road, obey all signs and keep driving. No looky-loos,” WSDOT tweeted Thursday afternoon.

Called the Easy Fire, it had grown to 300 acres in timber at 10:30 a.m. Thursday with no containment in the Okanogan-Wenatchee National Forest near southeastern Whatcom County, according to InciWeb.

InciWeb said the fire was reported at 7:30 p.m. Wednesday east of Newhalem and west of Mazama.

The fire was sparked by a lightning strike, InciWeb said. The National Weather Service warned of lightning storms without rain over the North Cascades and issued a Red Flag Warning on Wednesday.

Whatcom County residents woke to a hazy sunrise because of smoke from the Easy Fire.

Air quality was expected the be good Thursday because ocean breezes will carry the smoke away, said Seth Preston of the Northwest Clean Air Agency.