OKLAHOMA CITY (AP) — Severe storms and tornadoes battered Oklahoma early Sunday, tossing cars and ripping roofs off buildings in the middle of the night and leaving tens of thousands of homes and businesses without power. Among numerous injuries, 11 people required hospitalization, authorities said.

Much of the damage occurred in and around the state capital, Oklahoma City, near the state’s center, although there were reports of damage at various points around the state and early morning storms set off tornado warnings that extended south to the Arkansas state line. Heavy rains caused flash flooding in some areas and one lightning-sparked house fire was reported.

More than 99,000 Oklahoma homes and businesses lost power during the overnight storms. By midday that number was reduced to fewer than 34,000. No fatalities had been reported as of midday.

Richard Thompson, forecast chief for the National Weather Service Storm Prediction Center in Oklahoma, said he believes six or more tornadoes hit the state overnight. Meanwhile, forecasters warned state residents to brace for more heavy rain and possible severe weather through Monday.

“We’re not done with it yet,” he said.

In the town of Choctaw, east of Oklahoma City, firefighters and police officers went door to door Sunday morning to ask about injuries.

“It leveled a complete neighborhood in Choctaw,” the town’s mayor, Chad Allcox, told The Associated Press. He added that debris hindered search and rescue efforts. “Power lines are down everywhere … a lot of the roads are blocked, hard to get through. Very large trees blocking roadways.”

Oklahoma City Fire Department spokesman Scott Douglas told the AP that heavy rain and the lingering threat of tornadoes in the early morning darkness complicated early search and rescue efforts, describing a first sweep of hard hit areas around 1:30 a.m.

“It was a heavy downpour. We were trying to sweep the area with another possibility of a tornado coming through,” he said. “So that was in the back of our minds, too.”

Emergency workers had to free two people from an overturned mobile home, including a woman injured when an air conditioner landed on her leg, Douglas said.

The scale of the damage came into clearer focus as daylight broke. Local television footage showed downed power lines, walls peeled off homes, overturned vehicles and neighborhood streets littered with debris.

Douglas said 11 people were transported to hospitals with injuries that were not life-threatening. “There were some other minor injuries, some walking wounded, that were going to get treatment on their own,” Douglas said.

Allcox said early weather warnings and tornado sirens likely saved lives.

A handful of shelters — including one opened at a casino by the American Red Cross — are available for displaced residents or those without power, the Oklahoma Department of Emergency Management said.

The Oklahoma Heart Hospital South also sustained damage, state health officials said.

At the University of Oklahoma, school officials had urged students and staff to seek shelter and move to the lowest floor as the storms approached campus after midnight. The National Weather Service office in Norman also issued urgent warnings, posting on social media that “If you’re in the path of this storm, take cover immediately!”

Parts of Oklahoma remained under risk for more heavy rainfall and thunderstorms later Sunday.