BIRMINGHAM, Ala. • A wave of storms pounded the Deep South on Wednesday, leaving a trail of splintered trees and damaged buildings, and forecasters said still stronger ones were on the way with the potential for massive tornadoes, downpours and hail the size of tennis balls.

While nearly 16 million people in the Southeast could see powerful storms, the Storm Prediction Center said, a region of about 3 million stretching from southeastern Arkansas and northeastern Louisiana across Mississippi into Alabama was at high risk for big twisters that stay on the ground for miles, straight winds up to 80 mph and destructive hail.

Possible tornadoes knocked down trees, toppled power lines and damaged homes in the Alabama communities of Burnsville and Moundville, where power was out and trees blocked a main highway.

“Downtown Moundville got it. Some roofs and stuff got taken off houses,” said Michael Brown, whose family owns Moundville Ace Hardware. and Building. “There’s a lot of trees down. I guess it had to be a tornado; it got out of here pretty fast.”

Additional damage was reported in Mississippi, where video showed an apparent tornado at Brookhaven. High winds blew down signs and and trees in northeast Texas.

Storms were possible all the way from northern Texas in the west to northern Illinois and as far east as the Carolinas, the forecasters said, and the weather service issued multiple tornado warnings in Texas, Mississippi and Alabama.

Tornado watches included parts of seven states.