ROXBURY — A long stretch of Route 17 was closed to traffic Thursday night after a day of driving rain caused the Swift River to flood.

A police dispatcher did not know how long the road would be closed. Public works crews were at the scene and police were monitoring the state of the river, which one witness said had completely washed over the road in at least one area.

Main Street in Roxbury was also washed out, according to a dispatcher, making some areas of town inaccessible. By 9 p.m., Department of Transportation workers were still placing barricades between Roxbury and Rangeley along Route 17.

The National Weather Service in Gray had been warning that flooding was likely in Western Maine as thunderstorms and heavy rain continued to batter the region.

Running alongside the Swift River for several miles, Route 17 is a common problem area for flooding.

Meteorologists said thunderstorms were expected to continue through the night. They warned of flash flooding and of “ponding” along roads in the western part of the state.

As of 8 p.m., no roads were closed in Androscoggin County, according to an emergency dispatcher.

An estimated 3,000 Central Maine Power Co. customers were still without service Thursday night, according to a CMP spokeswoman. Of that number, about 1,700 were customers in York and Cumberland counties who lost power when a second line of storms came through the area late Thursday afternoon.