Last Updated Monday at 6:41 p.m. ET
OKLAHOMA CITY A mix of volunteers and first responders began combing through debris in the Oklahoma City area Monday evening to look for survivors after neighborhoods were flattened by a mile-wide tornado.
The National Weather Service says the devastating twister, one of several created by a storm system that swept through nation's midsection the past 36 hours, reached winds up to 200 mph. Television footage on Monday afternoon showed homes and buildings that had been reduced to rubble in Moore, Okla., south of Oklahoma City. CBS News correspondent Anna Werner reports much of the area smelled of gas. Residents walked around in shock. A high school, elementary school, movie theater and hospital were among buildings hard hit.
Although there was no official word on casualties, Oklahoma Gov. Mary Fallin said "it would be a miracle if people didn't get harmed in this story."
One woman told CBS News affiliate KWTV she and her two children survived by hiding in the bathtub. "Everything is gone," she said through tears. "Our whole house is gone. Everything except for where we were was gone."
Hospital officials remain on emergency alert, although KWTV reports there are already multiple fatalities. Patients were evacuated from the hospital that was hit..
"We just need patience at this point of time, and we need prayers," Oklahoma City Manager Jim Couch told CBS "Evening News" anchor Scott Pelley.
KWTV also reported that emergency personnel were rushed toward Plaza Towers Elementary school in south Moore to rescue students and staff that were trapped. All kids were accounted for, with some minor injuries reported, but the building was obliterated from receiving a direct blow from the tornado. Several children were pulled out alive from the rubble
Moore was hit hard by a tornado in 1999. The storm had the highest winds ever recorded near the earth's surface.
Sunday's severe weather caused two deaths and at least 21 injuries. Earlier Monday, spokeswoman Amy Elliot of the Oklahoma state medical examiner's office identified the two people confirmed dead from Sunday's storms as 79-year-old Glen Irish and 76-year-old Billy Hutchinson. Both men were from Shawnee.
Tornadoes were reported Sunday in Iowa, Kansas and Oklahoma as part of a storm system that stretched from Texas to Minnesota. Oklahoma's governor has declared a state of emergency in 16 counties across the state.
The powerful system spawned baseball-sized hail, and winds strong enough to flip over tractor trailers, littering them across a major interstate, reports correspondent Anna Werner.
The worst of the damage Sunday appeared to be at the Steelman Estates Mobile Home Park located amid gently rolling hills about 35 miles southeast of Oklahoma City.
"It took a dead hit," resident James Hoke said. Emerging from a storm cellar where he sought refuge with his wife and two children, Hoke found that their mobile home had vanished. "Everything is gone."
Hoke said he started trying to help neighbors and found his wife's father covered in rubble.
"My father-in-law was buried under the house. We had to pull Sheetrock off of him," Hoke said.
Forecasters had been warning of bad weather since last Wednesday and on Sunday said conditions had ripened for powerful tornadoes. Wall-to-wall broadcasts of storm information spread the word Sunday, leaving Pottawatomie County Sheriff Mike Booth grateful.
"There was a possibility a lot more people could have been injured," Booth said. "This is the worst I've seen in Pottawatomie County in my 25 years of law enforcement."
- Watch live coverage of the storm from CBS Oklahoma affiliate KOTV
- National Weather Service Storm Prediction Center
Hearing on the radio that a violent storm was approaching her rural Oklahoma neighborhood, Lindsay Carter took advantage of the advanced warning, gathered her belongings and fled. When she returned, there was little left of the community she called home.
She had heard on a radio broadcast that a storm that had originated southwest of Oklahoma City was headed toward Shawnee.
"We got in the truck and left," Carter said. With upward of 30 minutes' notice for Pottawatomie County, Carter had time to leave one of the few frame homes in Steelman Estates -- and most of her house was intact when she returned.
"I walked up, and the house was OK. Part of the roof was gone," she said.
The scene was different a short distance away.
"Trees were all gone. I walked further down and all those houses were gone," she said.
Following the Oklahoma twisters, local emergency officials went from home site to home site in an effort to account for everyone. Keli Cain, a spokeswoman for the Oklahoma Department of Emergency Management, said that, many times in such situations, people who are not found immediately are discovered later to have left the area ahead of the storm.
A storm spotter told the National Weather Service that the tornado left the earth "scoured" at the mobile home park. At the nearby intersection of Interstate 40 and U.S. 177, a half-dozen tractor-trailers were blown over, closing both highways for a time.
"It seemed like it went on forever. It was a big rumbling for a long time," said Shawn Savory, standing outside his damaged remodeling business in Shawnee. "It was close enough that you could feel like you could reach out and touch it."
Gov. Mary Fallin declared an emergency for 16 Oklahoma counties that suffered from severe storms and flooding during the weekend. The declaration lets local governments acquire goods quickly to respond to their residents' needs and puts the state in line for federal help if it becomes necessary.
Heavy rains and straight-line winds hit much of western Oklahoma on Saturday. Tornadoes were also reported Sunday at Edmond, Arcadia and near Wellston to the north and northeast of Oklahoma City. The supercell that generated the twisters weakened as it approached Tulsa, 90 miles to the northeast.
"I knew it was coming," said Randy Grau, who huddled with his wife and two young sons in their Edmond home's safe room when the tornado hit. He said he peered out his window as the weather worsened and believed he saw a flock of birds heading down the street.