Twisters hopscotched across the Deep South, and, along with brutal, straight-line winds, knocked down countless trees, blew the roofs off homes and left many Christmas celebrations in the dark. Holiday travelers in the nation's much colder midsection battled treacherous driving conditions from freezing rain and blizzard conditions from the same fast-moving storms.

As predicted, conditions were volatile throughout the day and into the night with tornado warnings still out for some parts of Alabama. The storms were blamed for two deaths, several injuries, and left homes from Louisiana to Alabama damaged.

In Mobile, Ala., a tornado or high winds damaged homes, a high school and church, and knocked down power lines and large tree limbs in an area just west of downtown around nightfall. WALA-TV's tower camera captured the image of a large funnel cloud headed toward downtown.

Rick Cauley, his wife, Ashley, and two children were hosting members of both of their families. When the sirens went off, the family headed down block to take shelter at the athletic field house at Mobile's Murphy High School.

"As luck would have it, that's where the tornado hit," Cauley said. "The pressure dropped and the ears started popping and it got crazy for a second." They were all fine, though the school was damaged. Hours after the storm hit, officials reported no serious injuries in the southwestern Alabama city.

Blizzards in mid-U.S.

Meanwhile, blizzard conditions hit the nation's midsection.

Earlier in the day, winds toppled a tree onto a pickup truck in the Houston area, killing the driver, and a 53-year-old north Louisiana man was killed when a tree fell on his house. Icy roads already were blamed for a 21-vehicle pileup in Oklahoma, and the Highway Patrol there says a 28-year-old woman was killed in a crash on a snowy U.S. Highway near Fairview.

The snowstorm that caused numerous accidents pushed out of Oklahoma late Tuesday, carrying with it blizzard warnings for parts of northeast Arkansas, where 25 centimetres of snow was forecast. Freezing rain clung to trees and utility lines in Arkansas and winds gusts up to 48 km/h whipped them around, causing about 71,000 customers to lose electricity for a time.

Blizzard conditions were possible for parts of Illinois, Indiana and western Kentucky with predictions of 10 to 17.5 centimetres of snow.

An apparent tornado also caused damage in Grove Hill, about 130 kilometres north of Mobile.

Mary Cartright said she was working at the Fast Track convenience store in the town on Christmas evening when the wind started howling and the lights flickered, knocking out the store's computerized cash registers.

"Our cash registers are down so our doors are closed," said Cartright in a phone interview.

Trees fell on a few houses in central Louisiana's Rapides Parish, but there were no injuries reported, said sheriff's Lt. Tommy Carnline. Near McNeill, Miss., a likely tornado damaged a dozen homes and sent eight people to the hospital, none with life-threatening injuries, said Pearl River County emergency management agency director Danny Manley.

Gov. Phil Bryant declared a state of emergency in the state, saying eight counties have reported damages and some injuries.

Fog blanketed highways, including arteries in the Atlanta area, which was expected to be dealing with the same storm system on Wednesday. In New Mexico, drivers across the eastern plains had to fight through snow, ice and low visibility.

At least three tornadoes were reported in Texas, though only one building was damaged, according to the National Weather Service.

500 flights cancelled

More than 500 flights nationwide were canceled by the evening, according to the flight tracker FlightAware.com. More than half were cancelled into and out of Dallas/Fort Worth International Airport that got a few centimetres of snow.

Christmas lights also were knocked out with more than 100,000 customers without power for at least a time in Texas, Arkansas, Oklahoma, Mississippi, Louisiana and Alabama.

In Louisiana, quarter-sized hail was reported early Tuesday in the western part of the state and a WDSU viewer sent a photo to the TV station of what appeared to be a waterspout around the Lake Pontchartrain Causeway in New Orleans. There were no reports of crashes or damage.

Some mountainous areas of Arkansas' Ozark Mountains could get up to 25 centimetres of snow, which would make travel "very hazardous or impossible" in the northern tier of the state from near whiteout conditions, the weather service said.

The holiday may conjure visions of snow and ice, but twisters this time of year are not unheard of. Ten storm systems in the last 50 years have spawned at least one Christmastime tornado with winds of 180 km/h or more in the South, said Chris Vaccaro, a National Weather Service spokesman in Washington, via email.

The most lethal were the storms of Dec. 24-26, 1982, when 29 tornadoes in Oklahoma, Missouri, Arkansas, Tennessee and Mississippi killed three people and injured 32.

In Mobile, a large section of the roof on the Trinity Episcopal Church is missing and the front wall of the parish wall is gone, said Scott Rye, a senior warden at the church in the Midtown section of the city.

On Christmas Eve, the church with about 500 members, was crowded for services.

"Thank God this didn't happen last night," Rye said.

The church finished a $1 million-plus US renovation campaign in June 2011, which required the closure of the historic sanctuary for more than a year.