(USA TODAY) A massive, mile-wide tornado with winds up to 200 mph killed at least 51 people Monday afternoon during 40 terrifying minutes of destruction across southern Oklahoma City and its suburbs.
The state medical examiner's office confirmed the number of deaths and said the toll was expected to rise. Multiple media outlets are reporting that at least 20 children are among the dead. USA TODAY could not independently confirm those reports.
Oklahoma area hospitals say they have treated about 120 people, including 50 kids.
PHOTOS: Oklahoma City hit by massive tornado
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Catastrophic damage was reported in Moore, which was flattened by another killer tornado that tracked the same path 14 years ago. Two elementary schools were destroyed, including one that took a direct hit.
Several children were pulled alive from the rubble of Plaza Towers Elementary, but some of their classmates were killed. About a mile away, the walls tumbled down at Briarwood Elementary. Miraculously, no one there died.
Three hospitals reported treating at least 120 injured, including some children rescued from the Plaza Towers school.
KFOR-TV reported that seven of the dead were children from Plaza Towers, where 75 students and staff members were huddled when the tornado struck. U.S. Rep. Tom Cole, who has lived in Moore for more than 50 years, told CNN the school did not have an underground shelter, just interior rooms with no windows.
At Integris Southwest Medical Center, 10 of 37 patients were in critical condition, a spokeswoman told the Associated Press. The hospital was treating five children, including two rescued from the elementary school. The OU Medical Center was treating 20 patients, including eight children.
More than 60 patients were being treated at Norman Regional Medical Center, some in critical condition, spokeswoman Kelly Wells said.
One patient was 9-year-old Kaileigh Hawkins, who was at one of the schools destroyed by the twister, Wells said. She is doing fine, but hospital officials have been unable to locate her parents.
The twister heavily damaged Moore Medical Center, ripping off its roof but causing no injuries. Staff had to relocate 30 patients to nearby Norman and another hospital.
A water treatment was knocked offline, and residents and businesses in southeastern Oklahoma City were advised to stop using water.
The preliminary rating of the tornado that hit Moore at 3:17 p.m. CT (4:17 p.m. ET) was put at EF-4, which means wind speeds from 166 to 200 mph, the National Weather Service said.
On May 3, 1999, a record-setting EF-5 tornado obliterated the city of 55,000 with winds measured at 318 mph, the highest ever on the earth's surface. The storm killed 36 people, injured hundreds and caused about $1 billion in damages.
The National Weather Service in Norman, Okla., said a tornado warning was in effect Monday afternoon for 16 minutes before the twister developed.
Rescuers were "going house to house and block to block to try and find any survivors that are out there and trapped,'' said state emergency management spokesman Jerry Lojka.
"We can only imagine that there are still many others there that are unaccounted for,'' he said.
Lojka said emergency management officials were working from an underground command center in Oklahoma City and did not yet know how many students were in the two elementary schools in Moore that were destroyed.
He said the funnel cut a path one and a quarter miles wide, traveling the entire width of the city.
"It went through an area and demolished complete subdivisions,'' he said. "It affected shopping centers, a theater, two schools that we know of.''
Officials said Monday evening that they would work all night to find survivors.
"Search-and-rescue efforts will continue through the night, as long as they need be," Moore Police Chief Jerry Stillings said at a news conference.
"We've been through this before,'' city manager Steve Eddy said, referring to the 1999 tornado and others over the years. "Our citizens are resilient.
Oklahoma Gov. Mary Fallin called up 204 Oklahoma National Guard personnel. She also spoke with President Obama, who offered her a direct line to his office and federal aid. She said she had been in touch with the Federal Emergency Management Agency.
Fallin had earlier declared emergencies for 16 Oklahoma counties, adding five more after the tornado roared roared through the Oklahoma City area and continued to the northeast.
Oklahomans who escaped the destruction counted their blessings and offered to help others less fortunate.
Holly Porter and her husband, Tracy, loaded up their truck with water and blankets, hitched up their horse trailer and set out on for what normally is a 40-minute drive to Moore, where their son and daughter-in-law live.
Because the tornado sucked away barns and fencing, she said, residents may have nowhere to keep their animals.
"We have 60 acres and we can take cows and horses," she said. "We're just going to help anyone we can."
The Porters had several anxious minutes when they couldn't reach their daughter-in-law, a substitute teacher at an elementary school. Eventually, Holly Porter got through and learned that their daughter-in-law's school had not been hit and that all the children were fine.
At Plaza Towers Elementary, end-of-the-year festivities that began last week continued Monday. First- and second-graders got their awards, with third-, fourth- and fifth-grade students scheduled to collect their honors Tuesday morning after "Rise and Shine" activities.
Monday night, the school's PTA Facebook page was awash in condolences and prayers.
Earlier in the day, Oklahoma, Texas, Kansas, Arkansas and Missouri had been under a tornado watch, meaning that conditions were favorable for tornadoes to develop within the next few hours.
The National Weather Service said it was tracking "a large and extremely dangerous tornado'' just west of Moore, The storm was moving to the northeast, and forecasters said they expected "large, destructive hail up to tennis ball size.''
Video aired by KFOR-TV showed a massive, dark funnel-shaped cloud over the area and, later, scenes of massive destruction. Entire neighborhoods were flattened.
On Sunday, a tornado packing winds as high as 200 mph, left two people dead in Oklahoma. Tornadoes and high winds injured more than 20 in the region.
More than 60 million Americans are at risk of severe storms Monday, with the primary targets including Oklahoma, Kansas, Missouri and Arkansas, the National Weather Service's Storm Prediction Center warned.
"Damaging wind gusts, large hail and tornadoes are possible in all areas," Weather Channel meteorologist Kevin Roth said.
Besides Oklahoma City, other cities at risk from severe weather Monday included Tulsa, St. Louis, Cedar Rapids, Iowa, and Minneapolis, said AccuWeather meteorologist Meghan Evans. Chicago, Detroit, Dallas and Indianapolis also are in the danger zone.
Sunday, there were 24 reports of tornadoes in five states, the Storm Prediction Center said. "In what has otherwise been a quiet spring for tornadoes, May 19 appeared to have been the second-most active day for tornadoes in the nation so far in 2013," Weather Channel meteorologist Jon Erdman said.
So far this year - not including this most recent five-day outbreak - severe storms have caused $3.5 billion in economic losses in the USA, said meteorologist Steve Bowen of global reinsurance firm Aon Benfield. Bowen says. Of that $3.5 billion, at least $2 billion was covered by insurance.
"By the time the current storm system finally winds down by the middle of this week, I wouldn't be surprised if this ends up as the costliest U.S. natural disaster event we've seen so far in 2013," said meteorologist Steve Bowen of global reinsurance firm Aon Benfield.
"Recent full-year severe weather-related insured losses were roughly $27 billion in 2011 and $15 billion in 2012 - the two costliest years on record," Bowen said. By this definition, "severe" weather means damage from thunderstorms or tornadoes, and does not include damage from hurricanes.
The storms in Oklahoma on Sunday that ripped off roofs and tossed big trucks like toys were part of a severe weather outbreak that stretched from Texas to Minnesota. Twisters were also reported Sunday in Iowa and Kansas.
The killer tornado that flattened portions of Shawnee, Okla., had wind speeds that were estimated as high as 200 mph, according to the National Weather Service.
Across Oklahoma, 21 people were injured, not including those who suffered bumps and bruises and chose not to visit a hospital, said Keli Cain, a spokeswoman for the Oklahoma Department of Emergency Management. Booth said six at Steelman Estates were hurt.
Interstate 40 was closed by the Oklahoma Highway Patrol after winds overturned semi-tractor trailer trucks and other vehicles, Newsok.com reported.
KFOR-TV showed footage of homes damaged and cars and trucks flipped from highways near Shawnee. Other video showed flashes from electrical transformers blowing out as they were hit by high winds or debris from the tornado near Edmond.
A tornado touched down in Golden City, Mo., early Monday morning and tore through two counties, Barton County Emergency Management Director Tom Ryan told CNN.
Meteorologist Kurt Kotenberg said a large low-pressure system is parking itself over the middle of the country and "really isn't going to move much over the course of the next few days. ... It's basically going to keep pulling up that nice Gulf (of Mexico) moisture that keeps fueling everything."
The threat of twisters comes less than a week after tornadoes left six dead, dozens injured and hundreds of homes destroyed in Texas and just shy of the two-year anniversary of the Joplin, Mo., twister.
Contributing: Susan Davis, Doug Stanglin, USA TODAY; The Associated Press.
William M. Welch, Doyle Rice and Doug Stanglin, USA TODAY