Huge floods ravaging West Virginia have killed at least 23 people, stranded hundreds and left tens of thousands without power overnight, officials said late Friday.

The threat of pop-up showers and overflowing rivers was still a concern late, and Gov. Earl Ray Tomblin said that search and rescue efforts remained a priority to help people trapped in swamped homes and cars. He said 200 National Guard members have been deployed in eight counties with about 300 more authorized to help with ongoing relief.

The storm system dumped 9 inches of rain on parts of West Virginia and trapped 500 people in a shopping center for more than 24 hours after a bridge washed out. Crews completed a temporary roadway Friday night and evacuated all those who wanted to leave although some decided to stay.

Dozens of other people had to be plucked off rooftops or rescued as waters quickly rose during the deluge.

The heavy rainfall over six to eight hours prompted the National Weather Service to call it a “one-in-a-thousand-year event.”