A mother and her young son were killed overnight when a tornado ripped through a rural town in northwest Louisiana, one of a swarm of twisters that touched down in the region as part of a massive winter storm system sweeping the United States.

First responders found the young boy deceased in a wooded area near his destroyed home in Keithville, Louisiana, a town of 300 people, late on Tuesday night after a tornado was spotted in the area, the Caddo Parish sheriff said in a statement.

Searchers later found the body of the boy’s mother under debris one street over from the destroyed home, Sheriff Steve Prator said, adding that an adult male was taken to a local hospital with unknown injuries.

“Several structures were damaged. Electrical lines and trees were also knocked down,” he said.

The tornado was one of 18 twisters reported in Texas, Louisiana and Mississippi late on Tuesday and early on Wednesday damaging structures and downing power lines and trees, the National Weather Service said.

In New Iberia, Louisiana, at least one person was injured and multiple people were trapped in a subdivision after at least one tornado touched down on Wednesday in the small city, which sits about 70 miles southwest of Baton Rouge, police said. Multiple homes and a hospital were damaged, the New Iberia police confirmed on Facebook.

Police warned residents to stay away from the damaged area as rescue efforts were under way.

The tornadoes were part of a sprawling winter storm that swept across the heart of the United States over the last two days, leaving parts of the Upper Plains and Midwest buried under blowing snow, closing schools and making roads impassible.

The system was expected to continue to cause blizzard-like conditions in the North and flooding with the potential of tornadoes in the South on Wednesday. It also threatened to cover parts of the East with ice and snow into Thursday.

Ice accumulation could down trees and power lines and cause power outages while making roadways hazardous, the NWS said, urging motorists to stay home.