A line of thunderstorms moving across the Deep South (search) on Tuesday unleashed an apparent tornado in Mississippi and roared into Alabama with enough wind to topple trees and knock out power to 50,000 customers.

At least 54 people were injured from Texas to Alabama.

Most of the Alabama power outages were between Birmingham and Tuscaloosa, where winds up to 50 mph knocked out car windows and blew down a billboard at a Tuscaloosa convenience store around lunchtime.

Police in Tuscaloosa (search) said one person was hurt as flying debris and stiff winds knocked out windows in several cars and a school bus. Shingles were peeled off the roof of a drug store.

Earlier, in Louisiana, about 40,000 customers were without power for a time west of New Orleans. Waterspouts forced temporary closure of the 24-mile causeway spanning Lake Pontchartrain, and rain swept across metropolitan New Orleans (search).

Power was restored quickly to most customers in both Louisiana and Alabama.

In Mississippi, at least three people were injured and more than a dozen homes were damaged when an apparent twister hit rural Smith County. Officials said most of the injuries involved cuts and bruises.

Gov. Ronnie Musgrove declared a state of emergency in central and southern areas of the state because of street flooding and downed trees.

The Rev. Danny Dickerson spent the morning checking on church members and other families along County Road 77.

One of the places he stopped was the mobile home of 96-year-old Pearlie Davis, who was uninjured even though one of two century-old oak trees had landed across her front porch.

"Her family and I were able to get in the back door to check on her," said Dickerson. "It turns out, she didn't know anything had happened."

Residents in southeast Texas began cleaning up and assessing the damage caused Monday by storms that spawned a series of tornadoes, flooded roadways and overflowed bayous and creeks.

Emergency medical workers treated more than 50 people in Fort Bend County, mostly for minor injuries.

As many as 21 tornadoes may have hit southeast Texas on Monday, said Charles Roeseler, a meteorologist with the National Weather Service.

An apartment complex in Baytown was hit by winds of 73 to 112 mph, Roeseler said, damaging 56 apartments and 12 nearby homes.

A Houston complex suffered damage to at least 30 apartments. One resident, Ray Anderson, 63, spent Monday night in his car with his dog and his hamster.

"It's a mess in there," Anderson said of his apartment. "There's one thing I can say: nobody got hurt. That's one good thing."