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Emergency officials and rescue crews are searching for survivors after a powerful storm system moved through the central and southern United States Sunday, spawning multiple tornadoes that killed at least 17 people.

On Monday night, Matt DeCample, a spokesman for Arkansas Gov. Mike Beebe's office, confirmed a 15th fatality from the powerful tornado that carved an 80-mile path of destruction through suburbs north of the state capital of Little Rock, Ark.

“Just looking at the damage, this may be one of the strongest that we've seen,” Arkansas Gov. Mike Beebe said Monday. “And preliminarily -- we haven't done any records checking -- but it looks like this is the largest loss of life that we've seen in one tornado incident since I've been governor.”

Beebe said he suspects it will take days to estimate the total amount of damage, but as of now, the primary focus is on search and rescue efforts and then security “for the rest of the people to ensure that people that don't need to be messing around in an area where they could loot or something.”

Brandon Morris, spokesman for the Arkansas Department of Emergency Management, said crews were sifting through the rubble Monday in the hope of uncovering survivors and to assess the full extent of the destruction.

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    "Right now, the main focus is life safety," Morris said. "We're trying to make sure everyone is accounted for."

    A spokesman for Faulkner County released the identities of the 11 people killed in the two towns. The victims included eight people in Vilonia, including two children, and three people in Mayflower.

    A father and his two daughters were killed in the same storm system on the Pulaski-Saline county line near Little Rock, while a 55-year-old woman died in White County in northern Arkansas.

    The tornado, which grew to be a half-mile wide, turned buildings into rubble and stripped the leaves and smaller branches off of trees.

    "There's just really nothing there anymore. We're probably going to have to start all over again," Vilonia Schools Superintendent Frank Mitchell said early Monday after surveying what had been a $14 million intermediate school set to open this fall.

    An Oklahoma county sheriff's dispatcher reported that one person had died in the town of Quapaw, near the state's borders with Kansas and Missouri. Fox News has also confirmed that another person died when a tornado hit Keokuk County, Iowa.

    The Arkansas tornado touched down about 10 miles west of Little Rock at around 7 p.m. local time and moved northeastward for at least 30 miles, the National Weather Service reported.

    The twister shredded cars, trucks and 18-wheelers stuck along Interstate 40 north of Little Rock. After the storm passed, tractor-trailer rigs tried to navigate through the damage to continue their journeys, while gawkers held smartphones to their windows to offer a grim glimpse of the destruction.

    State troopers went vehicle-to-vehicle to check on motorists and said with genuine surprise that no one was killed.

    "About 30 vehicles -- large trucks, sedans, pickup trucks -- were going through there when the funnel cloud passed over," said Bill Sadler, a spokesman for the Arkansas State Police.

    Karla Ault, a Vilonia High School volleyball coach, said she sheltered in the school gymnasium as the storm approached. After it passed, her husband told her their home was gone -- reduced to the slab on which it had sat.

    "I'm just kind of numb. It's just shock that you lost everything. You don't understand everything you have until you realize that all I've got now is just what I have on," Ault said.

    The National Weather Service in North Little Rock said it was virtually certain that the Mayflower and Vilonia storm would be rated as the nation's strongest twister to date this year.

    "It has the potential to be EF3 or greater," said meteorologist Jeff Hood. EF3 storms have winds greater than 136 mph. "Based on some of the footage we've seen from Mayflower and where it crossed Interstate 40, things were wrecked in a very significant way."

    From communities west of Little Rock to others well north of the capital, emergency workers and volunteers were going door-to-door checking for victims.

    "It turned pitch black," said Mark Ausbrooks, who was at his parents' home in Mayflower when the storm arrived. "I ran and got pillows to put over our heads and ... all hell broke loose."

    "My parents' home, it's gone completely," he said.

    Becky Naylor, of Mayflower, said she and her family went to their storm cellar after hearing that tornado debris was falling in nearby Morgan. Naylor, 57, said there were between 20 and 22 people in the cellar and they were "packed like sardines."

    "Everyone is welcome to come into it," she said. "In fact, people were pulling off the highways and were just running in."

    She said the men held the cellar doors shut while the tornado's winds tried to rip them open.

    "It sounded like a constant rolling, roaring sound," she said. "Trees were really bending and the light poles were actually shaking and moving. That's before we shut the door and we've only shut the door to the storm cellar two times."

    The White House issued a statement in which President Barack Obama promised that the federal government would help in the recovery and praised the heroic efforts of first-responders and neighbors.

    "Your country will be there to help you recover and rebuild as long as it takes," Obama said.

    The Arkansas tornado was one of several that touched down Sunday as a large storm system moved through parts of the Plains, Midwest and South.

    Less than two hours before the Arkansas tornado struck, a twister hit the small northeastern Oklahoma community of Quapaw, killing at least one person and injuring six others, Ottawa County sheriff's dispatcher Kelli Soechs said. Earlier Sunday, another Ottawa County sheriff's dispatcher reported that two people were killed. Soechs declined to explain the discrepancy.

    Five of the six injured in Quapaw were treated and released from Baptist Regional Health Center in Miami, Okla., said hospital spokeswoman Kristie Wallace. The sixth, who was in fair condition with a broken bone, was kept overnight, she said.

    Ottawa County Emergency Management director Joe Dan Morgan said Quapaw, which has about 900 residents, was heavily damaged by the tornado.

    "Looks like about half of town got extensive damage as well as the fire department," Morgan said.

    After hitting Quapaw, the tornado moved northward into Kansas and struck Baxter Springs, a city of about 4,200 residents about 5 miles away. Cherokee County, Kan., sheriff's dispatcher Josh Harvey said the tornado that hit Baxter Springs injured several people and caused extensive damage, but that no deaths had been reported. He said first responders were going from house to house checking on residents' wellbeing.

    Tornadoes also touched down Sunday in Nebraska, Iowa and Missouri, including one northwest of Joplin, Mo., where a massive tornado in May 2011 killed 161 people, injured many others and leveled a large swath of the city. Sunday's twister didn't hit Joplin.

    The first reported tornado Sunday touched down in a rural area in central in Nebraska. The weather service said it remained on the ground for only a short time, and there were no immediate reports of damage.

    Gusts of up to 60 mph were registered during a storm that hit southeastern Iowa on Sunday that damaged several buildings, including a barn that injured someone when it was blown over.

    Earlier Sunday afternoon, a strong line of storms moved through west-central Missouri, bringing winds that reached 70 mph hour near Chillicothe, Mo., that toppled some trees.

    The Missouri Highway Patrol also reported a tractor-trailer was blown onto its side on Interstate 70 about 30 miles east of Kansas City about 1 p.m. No one was injured. The weather service received a report from Plattsburg, Mo., where an anemometer measured 58 mph before it blew away. Golf ball-sized hail was reported at Overland Park, Kan., and Trimble, Mo.

    Sunday was also the third anniversary of a 122-tornado day, which struck parts of Mississippi, Alabama, Tennessee, Virginia and Georgia and killed 316 people.

    The Associated Press contributed to this report.