An apparent tornado caused damage in the west Alabama town of Grove Hill, located about 80 miles (130 kilometres) north of Mobile.
Meanwhile, blizzard conditions were hitting the nation's midsection.
No injuries were confirmed immediately, but fire crews were still making door-to-door checks in the hardest hit areas of Mobile. The Mobile Fire-Rescue Department, which was providing storm updates through Twitter, said a high school was damaged and that there was a gas leak at a nearby apartment building.
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 113 mph (182 kph) or more in the South, said Chris Vaccaro, a National Weather Service spokesman in Washington, via email.
On Christmas Eve, the church with about 500 members, was crowded for services.
MOBILE, Ala. - A Christmas Day tornado outbreak left damage across the U.S. South while holiday travellers in the much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions.
Conditions were volatile throughout the afternoon and into the night with tornado warnings in Alabama and the Florida Panhandle. The storms were blamed for two deaths, several injuries, and left homes from Louisiana to Alabama damaged.
Earlier in the day, winds toppled a tree onto a pickup truck in the Houston area, killing the driver. Icy roads already were blamed for a 21-vehicle pileup in Oklahoma, and the Highway Patrol says a 28-year-old woman was killed in a crash on a snowy U.S. Highway near Fairview.
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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.
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.
"We haven't verified what it was, but we have an area that we heard has damage to homes," she said.
Associated Press writers Jay Reeves in Birmingham, Alabama, Ramit Plushnick-Masti in Houston, Chuck Bartels in Little Rock, Arkansas, and AP Business Writer Daniel Wagner in Washington, contributed to this report.
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.
In Mobile, Alabama, a tornado or high winds damaged homes and knocked down power lines and large tree limbs in an area just west of downtown around nightfall, said Nancy Johnson, a spokeswoman for the Mobile County Commission. WALA-TV's tower camera captured a large funnel cloud headed toward downtown.
At least three tornadoes were reported in Texas, though only one building was damaged, according to the National Weather Service. Tornado watches were in effect across southern Louisiana and Mississippi.
The snowstorm that caused numerous accidents pushed out of Oklahoma late Tuesday, carrying with it blizzard warnings for parts of northeast Arkansas, where 10 inches (25 centimetres) of snow was forecast. Freezing rain clung to trees and utility lines in Arkansas and winds gusts up to 30 mph (48 kph) whipped them around, causing about 71,000 customers to lose electricity.
Nasty storms, tornadoes cross South; blizzard conditions in mid-US; 2 deathMore than 400 flights nationwide were cancelled 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 inches (centimetres) of snow.
The church finished a $1 million-plus renovation campaign in June 2011, which required the closure of the historic sanctuary for more than a year.
"We've had some pretty heavy weather," said Cartright in a phone interview. "Our cash registers are down so our doors are closed."
Christmas lights also were knocked out with more than 100,000 customers without power in Texas, Arkansas, Oklahoma, Mississippi, Louisiana and Alabama.
Blizzard conditions were possible for parts of Illinois, Indiana and western Kentucky with predictions of 4 to 7 inches (10 to 17.5 centimetres) of snow.
Trees fell on a few houses in central Louisiana's Rapides Parish but there were no injuries reported and crews were cutting trees out of roadways to get to people in their homes, said sheriff's Lt. Tommy Carnline. Near McNeill, Mississippi, 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.
"Thank God this didn't happen last night," Rye said.