(CNN) -- At least five people were killed in Oklahoma on Monday after a severe storm system spawned multiple tornadoes across the state, the state emergency management department said.
Three people died in Cleveland County, just west of Tecumseh, Oklahoma, said Albert Ashwood, director of the state emergency management department, and another was reported dead near Choctaw, east of Oklahoma City, Oklahoma. The location in Oklahoma of the fifth person who died was unknown late Monday night.
Brenda Finkle, director of corporate communications for Norman Regional Health System, said the company's hospital in Norman admitted eight patients Monday night in critical condition with crush injuries and head trauma.
At least 25 other people filled the waiting room of Norman Regional Hospital with lacerations and head wounds, Finkle said, adding hospital staff expected more patients to continue to seek treatment.
Another 20 people were either getting medical care or awaiting treatment at Moore Medical Center, just north of Norman, according to Finkle.
OU Medical Center in Oklahoma City, Oklahoma, received two patients with broken bones, according to spokesman Allen Poston.
The Oklahoma Department of Emergency Management reported seven injuries.
Video out of Norman showed overturned cars, snapped utility poles, downed trees and severely damaged homes. Several mobile homes were blown to pieces in one neighborhood where debris littered yards and streets alongside large trees ripped straight from the ground.
A truck stop east of Oklahoma City was demolished, taking a direct hit from one of the tornadoes, according to a spokeswoman for Love's Travel Stops and Country Stores.
Motorists pulled off Interstate 40 and sought shelter in the truck stop's large coolers and restrooms before the tornado tore the roof off the building, blew out car windows and overturned tractor-trailers, spokeswoman Christina Dukeman said.
Video showed people outside the truck stop receiving treatment for minor injuries. Laura O'Leary, a spokeswoman for the Emergency Medical Services Authority, said seven people were transported from around the immediate area to local hospitals in good and fair condition, "a miraculously low number ... considering the volume of area the tornado covered."
Love's employee Charlescie Greenway said she and two other women made it to one cooler before the twister tore through the building.
"The three of us were kind of trapped in there, holding the door shut, praying to God that we don't die and that everybody else was safe," Greenway told CNN affiliate KWTV, adding, "it was really scary -- the wind was like trying to pull the door off the latch."
Sammy Ward and his partner rode the twister out in their truck in the parking lot.
"It started hailing and then it quit hailing and then all of a sudden the wind hit and it just went dark and here went everything," Ward told KWTV. "Trucks went to rocking ... and next thing we know the whole roof and everything was gone."
Ward, who said he felt "very lucky," said the event lasted two to three minutes.
Ashwood said crews were working to assess the damages in at least 13 counties, adding "numerous" homes had been affected.
The American Red Cross opened at least two shelters in McCloud, Oklahoma, and Tecumseh, Oklahoma, and continued to assess needs across the state.
More than 31,000 homes were without power in the metro Oklahoma City area -- nearly 15,000 in Norman alone, according to Oklahoma Gas & Electric.
Ashwood said preliminary reports out of Norman indicate the damages are "similar to what you would see with an EF3" tornado, referring to the Enhanced Fujita Scale for measuring the strength of tornadoes. An EF3 is capable of producing winds up to 165 mph.
CNN iReporter Rebecca Barbato said tornado sirens were going off in her neighborhood in Moore, just north of Norman, when tennis-ball-sized hail began raining down on her roof.
Other tornadoes were reported in Yukon, Medford and Shawnee in Oklahoma, and in Wichita, Kansas.
The storms struck around 5 p.m. CT (6 p.m. ET).
Meteorologists warned throughout the day Monday of the potential for tornadoes.
CNN's Devon Sayers and Sarah Aarthun contributed to this report.