CHARLESTON, W.Va. (AP) — The National Weather Service says storm-related damage indicates that a rare tornado touched down in West Virginia.

The weather service tweeted that a tornado hit the Alum Creek area Monday night along U.S. Route 119 southwest of Charleston. The weather service says a survey team is looking at damage in other areas Tuesday in Kanawha County, where large trees toppled onto homes and roads.

The weather service is still determining the tornado's strength.

With its vast network of hills and mountains, West Virginia averages two tornadoes a year.

Monday's storm left more than 20,000 Appalachian Power customers without electricity. Charleston's Yeager Airport tweeted it was operating on backup generators. Workers at West Virginia's Capitol complex went home at midday Tuesday when the power was turned off campuswide as part of repair and restoration efforts.