ST. LOUIS, MO. (AP) — At least four people died and authorities were searching from building to building for people who were trapped or hurt after severe storms including a possible tornado swept through St. Louis.

The storms Friday afternoon tore roofs off some buildings, ripped bricks off of siding and downed trees and power lines as residents were urged to take cover.

St. Louis Mayor Cara Spencer confirmed the deaths at a media briefing.

“This is truly, truly devastating,” Spencer said, adding that the city was in the process of declaring an emergency.

National Weather Service radar indicated that a tornado touched down between 2:30 p.m. and 2:50 p.m. in Clayton, Missouri, in the St. Louis area. The apparent tornado touched down in the area of Forest Park, home to the St. Louis Zoo and the site of the 1904 World’s Fair and Olympic Games the same year, Pfahler said.

At Centennial Christian Church, City of St. Louis Fire Department Battalion Chief William Pollihan told The Associated Press that three people had to be rescued after part of the church crumbled. One of those people died.

“Pray for our church,” Centennial Christian posted on its Facebook page.

Jeffrey Simmons Sr., who lives across the street from the church, heard an alert on his phone and then the lights went out.

“And next thing you know, a lot of noise, heavy wind,” he said. He and his brother went into the basement. Later, he realized it was worse than he thought: “Everything was tore up.”

Simmons said the woman who died was a member of the church who was there every day.

Downed trees and stop lights also caused traffic gridlock during the Friday afternoon commute, and officials urged people to avoid driving if possible.

“If you do not have to travel, PLEASE STAY HOME,” the St. Louis Metropolitan Police Department said in a social media post.

The upper stories of the Harlem Taproom’s brick building were demolished when the storm came through, leaving piles of bricks around the outside. About 20 people were inside, but they huddled in the back of the building and none of them were hurt, the St. Louis Post-Dispatch reported.

Christy Childs, a spokesperson for the Saint Louis Zoo, said in a text that the zoo would remain closed Saturday because of downed trees and other damage. Childs said all animals were safe and that there were no reports of significant injuries to staff, guests or animals.

“We can’t definitively say whether or not it was a tornado — it likely was,” National Weather Service meteorologist Marshall Pfahler said. Radar also confirmed a tornado above Venice, Illinois, on Friday afternoon. Venice is northeast of St. Louis, just across the Mississippi River.

The storms were part of a severe weather system that spawned tornadoes in Wisconsin, downed trees, left thousands without power in the Great Lakes region and brought a punishing heat wave to Texas.

Appalachia and Midwest face danger

Weather forecasters warned that severe storms with hail and even hurricane-force winds could hobble parts of Appalachia and the Midwest on Friday. Tornadoes were also a risk there.

The National Weather Service said residents in Kentucky, southern Indiana, southern Illinois, parts of Tennessee, Missouri, Arkansas and Ohio should brace for intense storms that could include baseball-sized hail.

The weather service’s Storm Prediction Center said that “strong, potentially long-track tornadoes and very large hail” could be expected. The threat for damaging winds in excess of 75 mph will increase into this evening as storms grow into larger clusters.

Ahead of Friday night’s anticipated storm, Appalachian Power, which serves 1 million customers in West Virginia, Virginia and Tennessee, said Friday it requested 1,700 additional workers from neighboring utilities along with sending its own crews from unaffected areas to assist with service restoration.

Faith Borden, a meteorologist in the National Weather Service Nashville office, said Friday that middle Tennessee could expect “all types of severe weather. Winds up to 70 mph. We’re talking seriously large hail up to 3 inches, which for us is big hail.”

Texas hit by heat wave

Texas, meanwhile, faced searing heat. A heat advisory was issued for the San Antonio and Austin, with temperatures at a blistering 95 F (35 C) to 105 (40.5 C). Parts of the southern East Coast, from Virginia to Florida, battled with heat in the 90s.

The National Weather Service Office for Austin/San Antonio said Friday the humidity coming in over the weekend is expected to make temperatures feel hotter.

“There are concerns of heat exhaustion for people that aren’t taking proper precautions when they’re outdoors,” meteorologist Jason Runyen said. He advised those affected to take breaks and stay hydrated.

Overnight Thursday, storms accompanied by booming thunder, lightning displays and powerful winds swept through parts of Wisconsin, Illinois, northern Indiana and Michigan — leaving scores of trees down and thousands of homes without power.

Several tornadoes touched down Thursday in central Wisconsin. None of the twisters have received ratings yet, said Timm Uhlmann, a National Weather Service meteorologist in Green Bay.

“We’re still gathering reports,” Uhlmann said. “We’re assessing some of the damage and still getting video and pictures. The damage that we have is fairly widespread. There was a lot of large hail. In Eau Claire was one report of softball-sized hail.”

No injuries have been reported.

Surveys also were underway Friday of damage in Michigan to determine if any tornadoes touched down there, said Steven Freitag, a meteorologist with the National Weather Service in White Lake Township, northwest of Detroit.

The storms were fueled by temperatures in the lower 80s that stretched from Illinois into Michigan and were activated by a cold front that pushed through, Freitag said.

By Friday evening, customers in Michigan were slowly seeing power return but more than 200,000 remained without it. An estimated 60,000 were without power in Indiana. Another 27,000 in total had no electricity in Illinois and Kentucky.

The threat of severe weather in Chicago delayed a Beyonce concert by about two hours Thursday at Soldier Field.

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Associated Press writer Haya Panjwani in Washington and Heather Hollingsworth in Kansas City, Missouri, contributed to this story.