DALLAS - Tornadoes swept through the Dallas area after dark on Saturday, leaving at least seven people dead either from the storm or related traffic accidents.

The Texas tornadoes followed days of tumultuous weather in the Southeast including unusual winter tornadoes that left 18 people dead there over the Christmas holiday.

National Weather Service Meteorologist Anthony Bain in Fort Worth said several tornadoes touched down in the Dallas area, although the full extent of damage would not be known until daylight Sunday.

The storms left homes with roofs blown away, vehicles mangled or turned upside down, churches damaged, power lines down, natural gas lines burst, trees toppled and debris strewed across neighborhoods. The damage stretched over about a 40-mile-long area from 20 miles south of Dallas to northeast of the city.

Joe Harn, police spokesman for Garland, about 20 miles northeast of Dallas, said four people were killed in vehicle accidents during the massive storm, but it's unclear if all four were in the same vehicle or how they died.

Three other people died in Collin County, about 45 miles northeast of Dallas, according to sheriff's deputy Chris Havey, although the circumstances were not immediately clear.

In the town of Rowlett near Garland, police spokesman Det. Cruz Hernandez said several people were injured.

"As of right now, we are still in the search and rescue mode. We still have some homes that have been demolished and not everyone in the homes has been accounted for," Hernandez said.

The twisters - accompanied by torrential rain, wind and some hail - were part of a weather system that could produce major flooding from north Texas through eastern Oklahoma, eastern Kansas, western Arkansas and parts of Missouri.

Passengers waiting for flights at Love Field, a major Dallas airport, were moved away from windows during the storm. Flights were temporarily halted from Dallas-Fort Worth International Airport. The Dallas Mavericks NBA game was delayed about half an hour because of the storm.

On the other side of Texas, a snowstorm accompanied by plunging temperatures, was expected to leave up to 16 inches of snow in West Texas and much of New Mexico through Sunday evening, according to NWS meteorologist Brendon Rubin-Oster in College Park, Md.

"It's going to be quite dangerous for anyone exposed to these elements," Rubin-Oster said.

In the Southeast, two more deaths linked to weather were reported Saturday in Mississippi, bringing that state's death toll from severe weather over Christmas to 10. Late Saturday, one death was reported in Alabama.

Flash flooding closed roads across Alabama and trapped motorists in rapidly rising waters.