A monstrous tornado at least half-a-mile wide roared through Oklahoma, flattening entire neighbourhoods destroying a school and leaving close to 100 dead.
At least 91 people were killed, including 20 children, and officials said the death toll was expected to rise.
The ferocious storm, with winds of up to 200mph, ripped through the suburb of Moore in a Midwest region of the US known as Tornado Alley.
Rescue crews worked through the night lifting bricks and parts of collapsed walls.
The storm laid waste to scores of buildings in Moore, a town of 41,000 people 10 miles south of Oklahoma City.
Block after block lay in ruins. Homes were crushed into piles of broken wood. Cars and trucks were left crumpled on the roadside.
Rescuers launched a desperate rescue effort at the elementary school, pulling children from heaps of debris.
More than 120 people were being treated at hospitals, including about 50 children. And search-and-rescue efforts were continuing today.
Families anxiously waited at nearby churches to hear if their loved ones were alive. A man with a megaphone stood near St Andrews United Methodist Church and called out the names of surviving children. Parents waited nearby, hoping to hear their sons' and daughters' names.
Amy Elliott, spokeswoman for the Oklahoma Medical Examiner's Office, said there could be as many as 40 more fatalities, including more children.
In video of the storm, the dark funnel cloud could be seen marching slowly across the green landscape.
As it churned through the community, the twister scattered shards of wood, awnings and glass all over the streets.
Oklahoma Governor Mary Fallin deployed National Guard troops and spoke to President Barack Obama, who declared a major disaster.
"Hearts are broken" for parents looking for their children, Ms Fallin said.
At Plaza Towers Elementary School, the storm tore off the roof, knocked down walls and turned the playground into a mass of twisted plastic and metal.
Children from the school were among the dead, but several students were pulled alive from the rubble. Rescue workers passed the survivors down a human chain to a field hospital in the car park.
James Rushing, who lives across the street from the school, heard reports of the approaching twister and ran to the school, where his five-year-old foster son, Aiden, attends classes.
"About two minutes after I got there, the school started coming apart," he said.
Tiffany Thronesberry said she heard from her mother, Barbara Jarrell, shortly after the tornado struck. "I got a phone call from her screaming, 'Help! Help! I can't breathe. My house is on top of me!'" Ms Thronesberry said. Her mother was saved by rescuers.
The tornado destroyed the city hospital and many businesses. Moore Mayor Glenn Lewis watched it pass from his jewellery shop. "All of my employees were in the vault," Mr Lewis said.
Country music star Toby Keith, who grew up in Moore, said his hometown would persevere. "Home town got hit for the gazillionth time. Rise again Moore Oklahoma," Keith tweeted.