(CNN) A string of deadly storms that ravaged some Southern states over the weekend could put millions more at risk as it moves north Monday.

At least 13 people were killed and dozens more injured as storms tore through Texas, Missouri, Arkansas, Tennessee and Mississippi over the weekend, spawning tornadoes and floods that left a trail of devastation.

Tornadoes tore roofs off homes, ripped trees out of the ground and tossed cars "around like toys," one witness said. Floods swept cars off the road and downed trees and power lines that flattened homes.

The storms were expected to move into Alabama Sunday evening and continue along a path extending to Michigan. A severe weather warning is in effect through Monday, putting 22 million people in six states from North Carolina to New York at risk of isolated tornadoes, high winds and large hail.

In Canton, Texas, "There are cars that have been thrown around like rag dolls," said Cliff Henthorn, who took this photo Saturday while visiting from Fort Worth.

In Texas, 'heartbreaking' devastation

At least three tornadoes touched down in northeast Texas on Saturday, leaving widespread damage in Van Zandt and Henderson counties, a rural area about 60 miles east of Dallas.

At least four were killed and 49 people were taken to area hospitals, Canton Mayor Lou Ann Everett said. One person is still unaccounted for. First responders from across the state went door to door on Sunday to look for survivors in more than 5,000 homes in the tornado's path, she said.

"It is heartbreaking and upsetting, to say the least," the mayor said.

Canton High School, which was used as a triage center, would be closed Monday, along with the rest of schools in Canton and Fruitvale, Everett said. A curfew is in effect in affected regions outside of the city of Canton.

Texas Gov. Gregg Abbott visited Canton on Sunday to survey the damage. He commended local officials and first responders for their work and called on Texans to donate money instead of supplies.

High winds tore limbs off trees and blew them onto roads, where they blocked traffic, according to reporter J.D. Miles of CNN affiliate KTVT . Vehicles in a lot were "tossed around like toys," he said.

The twisters interrupted First Monday Trade Days, one of the largest outdoor collectibles markets in the United States. Crowds of attendees were forced to take shelter in bathrooms, CNN affiliate KLTV reported.

"We saw the the tornado drop out of the sky," said Fort Worth resident Cliff Henthorn, who was in Canton for the event. "This was crazy. It completely looks like a can opener opened this truck right in front of me. "

Fort Worth's Cliff Henthorn took this photo after Saturday's tornadoes in Canton, Texas.

The tornado hit about a mile from 17-year-old Hayley Herron's house. The next day everyone was still in shock, she said.

"The damages were horrible," she said. "Power lines and fences torn down over the roads, my friends' homes destroyed, there were buildings completely gone. Trees were split and thrown across pastures."

Death toll rises

In Arkansas, where Gov. Asa Hutchinson declared a state of emergency in response to flooding, at least four people died in the storms, the state Department of Emergency Management said.

"Our prayers go out to the families who lost loved ones in the heavy rain and storms last night. I also thank our first responders who have worked tirelessly to provide assistance," Hutchinson said.

One woman died when a tree fell on a mobile home in De Witt, about 80 miles east of Little Rock, ADEM spokeswoman Whitney Green said.

In Carroll County, the body of a 24-year-old woman was found after it washed up in a creek. Officials in Washington County reported that a water rescue turned into a recovery without giving more detail on the victim.

Another death in Cleborne County was included in the ADEM's death toll. The agency did not provide further details, but the Cleborne County Sheriff's Office said on its Facebook page that Fire Chief Doug Deckard died "in a tragic accident" while checking an area during a thunderstorm.

The agency did not include in its count the death of a 10-year-old girl in Springdale. The girl and her brother climbed a fence near a creek and the girl was swept away by rushing waters, Springdale Police said in a Facebook post. Her brother was safe and the girl's body was found around midnight, police said.

Officials in Mississippi blamed the weather for at least two deaths. In Rankin County, a child died from an electric shock in floodwater. Authorities did not provide information on the other death.

In Nashville, Tennessee, a 2-year-old girl died after she was struck by a metal soccer goal that was blown over by high winds, Nashville police said Sunday.

Missouri governor: 'Stay home. Stay safe'

At least two people died in the storms that began Friday in Missouri, bringing heavy rain and flooding.

A couple was left stranded in their car when flood waters began to rise in Christian County, officials said. Despite the man's efforts to rescue his wife, their car was swept away with the 72-year-old woman inside. The woman's body was found Saturday in a field near Clever, Missouri.

A second death was reported Sunday, though information about the circumstances was not immediately available.

At least 150 roads, mostly in southern Missouri, were closed by flooding, the Missouri Department of Transportation said.

A total of 111 evacuations and 136 water rescues were reported as of Sunday, Gov. Eric Greitens said.

"Our standing first responders are working to protect life and property in this storm. Grateful for their work. Stay home. Stay safe."