Thousands without power as swarm of tornadoes slam into Oklahoma City area

At least 11 people were injured Sunday morning and about 100 homes were damaged or destroyed when multiple tornadoes swarmed the Oklahoma City area.

Officials issued tornado warnings Sunday, including one for the University of Oklahoma's Norman campus.

One of the twisters is thought to have touched down directly in Oklahoma City, where most of the injuries occurred. Police and fire officials said the people hurt were being treated at hospitals for non-life-threatening injuries.

The Oklahoma City Fire Department said on Sunday that it had successfully rescued two adults who were trapped in an overturned mobile home.Additionally, it said firefighters had responded to individuals stranded in their vehicles due to flash-flooding conditions.

As of Sunday afternoon, there were no reports of fatalities.

However, Oklahoma City officials reported that 39 structures were destroyed, another 43 sustained major damage, and 54 structures received minor damage.

Officials said the damage assessment was ongoing, and Gov. Kevin Stitt issued an emergency declaration for six counties late Sunday.

In addition to the damaged or destroyed structures, power lines were downed, trees were toppled and gas lines were broken when the possible twisters tore through the area during a four-hour period beginning around 11 p.m. Saturday, Nolan Meister, a meteorologist for the National Weather Service (NWS) in Norman, Oklahoma, told ABC News on Sunday.

"We are estimating that there were at least six tornadoes and potentially as many as 12," Meister said, adding that the severe weather also produced flash flooding and large hail in the area.

He said the NWS has confirmed "a couple" of the tornadoes and is working to confirm the others.

One possible tornado struck the community of Choctaw, about 17 miles east of Oklahoma City, at about 1 a.m., according to the Choctaw Police Department.

The suspected twister ripped through the Railhead Estates in Choctaw, causing "major damage" to homes and prompting firefighters and police to go door-to-door checking on residents, authorities said in a statement.

Several people were reported suffering minor injuries in the incident, police said.

"There is significant damage to homes in the area," police said in the statement. "We have opened the gymnasium at Choctaw Elementary for anyone that needs a temporary place for rest and shelter."

The nearby city of Harrah also sustained damage, according to the Choctaw Police Department, adding that people were taking shelter at a local casino.

Images of damage also emerged Sunday in Newcastle, about 14 miles south of Oklahoma City.

Meister told ABC News that around 9 a.m. on Sunday, all the tornado warnings in the area had been lifted.

However, he said that more severe weather was headed to the Oklahoma City area. The NWS issued several tornado warnings in the Oklahoma City area Sunday afternoon and said thunderstorms are also expected.

The NWS said Sunday afternoon that a twister that touched down in southeast Oklahoma City was rated as an EF3 on the Enhanced Fujita Scale, meaning it packed wind speeds of 136-165 mph. Officials said another tornado that hit Comanche in Stephens County was rated as at least an EF2 tornado packing wind speeds of 111-135 mph.

The NWS forecasted more severe weather throughout Sunday for the Oklahoma City area.

Among the emergency tornado warnings issued Sunday was one that prompted students and staff at the University of Oklahoma's Norman campus to shelter in place, officials said.

The warning was posted at 1:22 a.m. on the school's official X account. The school issued additional warnings at 1:55 a.m. and 2:02 a.m.

"Seek shelter NOW inside the building you are in," the first message said. "Move to lowest floor/interior."

At the time, the NWS said it was watching for tornadoes throughout central and eastern Oklahoma. A small area within northwest Texas was also under watch, the agency's Storm Prediction Center said in an urgent update at 1:40 a.m.

The center said about 15 minutes later it had seen several "discrete supercells" that had "matured within the open warm sector across OK."

"A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area," the center said. "Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings."

Oklahoma's governor reminded residents at a press conference on Sunday evening that Red Cross shelters were open for services and resources, while the state emergency center remains activated.

With over 30,000 households experiencing power outages, Stitt said that the state will prioritize having polling stations open -- with power available -- by Election Day. If there are any issues, he assured, voters will be notified and rerouted as needed.

ABC News' Kenton Gewecke and Vanessa Navarrete contributed to this report.