BENTON, La. (AP) — Authorities in Louisiana said Saturday said at least three people have died in connection with a severe storm that is sweeping across parts of the U.S. Gulf Coast and Southeast.

The Bossier Parish Sheriff's Office said on its Facebook page that the bodies of an elderly couple were found near their demolished trailer by firefighters. A search for more possible victims was underway. The Sheriff's Office also said the roof of Benton Middle School was damaged and “that water damage from the sprinkler system has flooded many rooms.”

The National Weather Service issued a tornado warning for Mississippi early Saturday. Homes were damaged or destroyed in Missouri, Oklahoma and Arkansas on Friday, but no injuries were reported. Downed trees and power lines were widespread.

According to PowerOutage.us, Louisiana and Mississippi had more than 54,000 power outages. Tennessee, Texas and Arkansas also reported outages exceeding 36,000.

The national Storm Prediction Center said Friday more than 18 million people in Louisiana, Arkansas, Texas and Oklahoma were at an enhanced risk of storms, including from strong tornadoes, flooding rains and wind gusts that could exceed 80 mph (129 kph), the speed of a Category 1 hurricane.

The weather service said parts of Texas would continue to be pelted with rain and snow Saturday. The storms already unleashed downpours that caused widespread flash flooding. Dallas police said one person died when a car flipped into Five Mile Creek west of downtown Dallas about 7 p.m. on Friday. Ahead of the storms, Dallas' Office of Emergency Management asked residents to bring in pets, outdoor furniture, grills, “and anything else that could be caught up in high winds to reduce the risk of flying debris."

On Alabama's Gulf Coast, Baldwin County canceled school activities including sporting events for Saturday. The weather service warned of flooding and the potential for 10-foot-high (3-meter-high) waves on beaches, where northern visitors escaping the cold are a common sight during the winter.

Many streams already are at or near flood levels because of earlier storms, and heavy rains could lead to flash flooding across the region, forecasters said. Parts of Arkansas, Tennessee, Mississippi, Missouri, Illinois and Indiana were under flash flood warnings or watches on Saturday.