The tornado that slammed into a town about 16 km west of the Arkansas state capital of Little Rock on Sunday evening, killing at least 15 people, grew to about 800m wide and was among a rash of tornadoes and heavy storms that rumbled across the centre and south of the US overnight, ending a lull in violent weather across America with a fury. The National Weather Service warned that more tornadoes, damaging winds and very large hail would strike in parts of Mississippi, Alabama, Tennessee and Louisiana on Monday.
It was among a rash of twisters and violent storms across the Midwest and South that killed 17 people in all on Sunday.
On Monday, tornados flattened homes and businesses and flipped trucks over on highways, killing two people in Alabama and one in Mississippi.
Most of the dead in Arkansas were killed in their homes in and around Vilonia, population 3 800. Fire-fighters on Monday searched for anyone trapped amid the piles of splintered wood and belongings strewn across yards. Hospitals took in more than 100 patients.
2014’s strongest US tornado
The tornado that hit the town and nearby Mayflower was probably the nation's strongest so far this year on the 0-to-5 EF scale, with the potential to be at least an EF3, which means winds greater than 218 kph, National Weather Service meteorologist Jeff Hood said.
It wrecked cars and trucks along Interstate 40 north of Little Rock. Also among the ruins was a new $14m intermediate school that had been set to open this fall.
A meteorologist with the National Weather Service in Arkansas said he was virtually certain the storm that hit the towns of Vilonia and nearby Mayflower would be rated as America's strongest twister to date this year.
Meteorologist Jeff Hood said the storm could have been an EF3, with winds greater than 218kph. He said officials are studying the environmental impact.
Storm ratings for Sunday's twisters were not immediately available. Before Sunday, the US had not had a tornado rated EF3 or higher since 17 November, a streak of 160 days, the fourth-longest on record. This also would be the latest date for a storm rated EF3 or higher. The previous latest big storm for a year was 31 March 2002.
‘Rolling, roaring sound’
Another twister killed a person in Oklahoma before crossing into Kansas to the north. A suspected tornado also struck in northwest Louisiana.
The Arkansas twister shredded cars and trucks along Interstate 40, the main corridor north of Little Rock. After the storm passed, big trucks tried to navigate through the damage as gawkers captured photos of the destruction.
Late Sunday, emergency workers and volunteers went door-to-door checking for victims and survivors.
Becky Naylor, aged 57, of Mayflower, said up to 22 people "packed like sardines" into her storm cellar as the tornado approached.
"People were pulling off the highways and were just running in," said Naylor.
Men held the cellar doors tight to prevent the tornado from ripping them apart.
"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 Arkansas Department of Emergency Management raised the Arkansas death toll to 16 early on Monday - eight adults and two children in Faulkner County, five people in Pulaski County and one in White County.
At a news conference in the Philippines, President Barack Obama sent his condolences and promised the government would help in the recovery.
Sunday was the third anniversary of a day when 122 tornados struck parts of Mississippi, Alabama, Tennessee, Virginia and Georgia and killed 316 people.
A home lies in ruins after a tornado yesterday tore through the area for the second time in three years in Vilonia, Arkansas. (Wesley Hitt, AFP)