South Dakota was the center of weather extremes Sunday, with a tornado damaging a small town and injuring at least nine people on the eastern side of the state and more than a foot of snow blanketing the Black Hills to the west.
The storms continued tearing up the country's heartland overnight, reportedly killing two people and injuring dozens in northeast Texas and southwest Arkansas.
CBS affiliate KSLA-TV reported that two victims were found dead in Nashville, Arkansas, about 50 miles north of Texarkana, according to the local sheriff's office. KSLA said many homes in the area were severely damaged as reported tornadoes touched down.
Several Great Plains and Midwest states found themselves in the path of severe weather during the weekend, including Texas, which saw at least two likely tornadoes.
In South Dakota, Gov. Dennis Daugaard said nine people were injured Sunday morning when a tornado tore through the tiny town of Delmont -- about 90 miles from Sioux Falls. None of the injuries was life threatening and seven of the nine had been treated and released from the hospital, Daugaard said. There were no fatalities.
South Dakota Red Cross representative Brian Shawn told CBS affiliate KELO on Sunday night that the organization was "trying to help at least get people a place where they can spend some time and relax and eat some food and have a roof over their head ."
South Dakota Department of Public Safety spokeswoman Kristi Turman said about 20 buildings were damaged and the town has no water, power or phones.
KELO said Delmont, a town of about 200 people, had been evacuated and non-residents were not being allowed in while emergency crews continued their work.
"Our house is flat. There is nothing left," said Stephanie Lunder, 34, of Delmont. She was with her husband and four children in the basement when the storm hit. The tornado heavily damaged a church where children attending Sunday school were forced to retreat to the basement, residents said.
In Texas, a likely tornado late Sunday night hit the small city of Van, about 70 miles southeast of Dallas, according to National Weather Service senior meteorologist Eric Martello.
Fire Chief Jeff Hudgens said Van sustained "some significant damage" to "multiple homes" and said agencies were responding to confirmed injuries.
Van Zandt County Fire Marshal Chuck Allen said in a written statement that the damage ranged from homes completely destroyed to trees and power lines torn down.
"Approximately 26 patients have been identified and transported to areas hospitals," said Allen.
Earlier in the day, another likely tornado ripped roofs off buildings and damaged trees near Denton, about 40 miles northwest of Dallas, according to National Weather Service meteorologist Tom Bradshaw. There were no immediate reports of injuries or fatalities.
Forecasters had issued tornado watches through Sunday evening for parts of Texas, Oklahoma, Arkansas, Iowa, South Dakota, Nebraska, Minnesota and Missouri.
The threat became a reality Sunday evening in the Iowa town of Lake City, as spotters said a quarter-mile-wide twister touched down repeatedly, tearing the roof clean off the local high school.
CBS affiliate KCCI in Des Moines reported that about 100 people were in the Lake City High School auditorium when the roof was pried off by the high winds.
Ashlee Taylor was among those inside. She told KCCI it was dark in the auditorium as the power had already gone out when the apparent tornado hit.
"We did hear the roof come off, and there was a change of pressure. I thought my ears were gonna pop, that's what it felt like to me," she told KCCI.
The station said there was extensive property damage and downed power lines, but there were no immediate reports of injuries.
The area also experienced torrential rains that led to widespread flash flooding. Authorities in Denton County said Sunday that two groups of people had to be airlifted by helicopters to safety.
CBS station DFW in Dallas reported that authorities couldn't reach those trapped by the flood waters with fire trucks because the water overflowing from a nearby creek was too high, so they called in the copters.
About 100 miles west of Fort Worth, people in the sparsely populated ranching and farming community of Cisco were left to clean up from Saturday's tornado that left one person dead and another in critical condition. Cisco Fire Department spokesman Phillip Truitt said the two people were near each other.
The National Weather Service said that tornado was rated an EF-3, with winds ranging from 136 to 165 mph. At least six buildings were damaged south of Cisco, as well as six others near Lake Leon, Truitt said.
A strong line of storms moved through the Dallas-Fort Worth area Sunday morning, forcing significant delays and a total of 100 flight cancellations at Dallas-Fort Worth International Airport and Dallas Love Field Airport.
Farther north, a late-season snow fell in parts of the Rockies, western Nebraska and western South Dakota.
National Weather Service meteorologist Kyle Carstens said between 10 to 18 inches of snow was on the ground Sunday morning in the Black Hills of South Dakota and totals could reach 20-24 inches by the time the system moves out. Rapid City, South Dakota, had 8-11 inches, accompanied by 20-30 mph winds.