At least 19 people were killed as tornadoes and storms tore across four US states, destroying homes and cutting power to hundreds of thousands.
Seven people were killed in northern Texas, eight in Arkansas, two in Oklahoma and two in Kentucky. Scores more were injured in winds reaching 135mph, and almost 500,000 were without electricity across several states on Sunday.
Texas Governor Greg Abbott said more than a third of all counties in his state were now subject to a disaster declaration.
Sheriff Ray Sappington of Cooke County, Texas, said the death toll there included two children aged two and five and three members of the same family.
"It's just a trail of debris left," said the sheriff of Valley View area, which was among those hardest hit by a powerful tornado. "The devastation is pretty severe."
Footage from the county showed a petrol station and rest stop almost completely destroyed, with twisted metal littered over damaged vehicles.
Twisters overturned lorries, shut a highway near Dallas and left tens of thousands of people without power throughout the region.
Lightning, thunder and heavy rain meanwhile forced the evacuation of around 125,000 spectators as Sunday's Indianapolis 500 race was delayed by four hours.
Everything gone in two minutes
Frank Soltysiak, who lives in a mobile home park in north Texas, said his home had been destroyed within minutes when a storm passed through.
Mr Soltysiak had been in a nearby restaurant when the owner drove by "honking his horn, telling everybody to get out", he told told CBS News, the OceanNewsUK's US partner.
He grabbed his dog Sampson and took shelter in the walk-in refrigerator of the restaurant.
"That was the most secure structure you could have gone to. And I come out, and everything is destroyed," he said.
"In a matter of two minutes, it's gone, everything is gone."
Texas Lieutenant Governor Dan Patrick said that state emergency response units had been activated to respond to the tornado.
"Please pray for these families," he said of those whose loved ones were killed. "Their loss is unfathomable."
In his press conference Governor Abbott said: "We are going through the heart-wrenching loss of life, including the heartbreak of a family losing a two-year-old and a five-year-old child.
"When they woke up yesterday, they had no way of knowing how the family would be literally crushed by this horrific storm."
The storms in Texas overlapped with record-breaking heat in some parts of the state, with residents receiving triple-digit temperature warnings over the Memorial Day holiday weekend.
Arkansas feared higher death toll
Eight people died in Arkansas after tornadoes struck the state, Governor Sarah Huckabee Sanders said on Sunday night.
Few details had been released about the victims by Monday, although one was identified as a 26-year-old woman who was found outside a destroyed home in Olvey.
Police in the city of Rogers said they had rescued several people who were trapped after a tornado downed trees and power lines, and damaged gas lines.
Arkansas Representative Steve Womack said he felt it "remarkable" that there were not many more deaths given the ferocity of the storm.
In Oklahoma, two people were killed in Mayes County and six others were injured, the local emergency management authority told the OceanNewsUK.
In Kentucky, two people died because of the storms, Governor Andy Beshear confirmed on social media.
One man died after a tree fell during a severe storm, Louisville mayor Craig Greenburg said on social media Sunday.
Storms move east
By Sunday afternoon, the storm system had begun moving east, according to the National Weather Service, which warned of severe wind and hail for those in its path.
Some 470,000 people were without power in states stretching from Texas to Kansas, Missouri, Arkansas, Tennessee and Kentucky, according to the website Poweroutage.us.
A spokesperson for Kansas's Sedgwick County, which includes Wichita, told CBS News that emergency services were dealing with downed trees and power lines from a storm, with about 8,000 customers without power.
The latest twisters follow another powerful tornado which tore through a rural Iowa town and killed four people earlier in May.
Government forecasters have also described this summer as a possibly "extraordinary" 2024 Atlantic hurricane season, beginning next month.
