Dozens more people are missing and entire towns were destroyed by about 30 tornadoes on Friday.
President Biden has declared a disaster in Kentucky, the worst-affected state.
At least 80 people have died in the state, including dozens in a candle factory, and the death toll is expected to rise above 100.
Kentucky Lieutenant Governor Jacqueline Coleman told the BBC the death toll was continuing to rise "with every hour".
"All of these numbers continue to unfold...," she said. "Our emergency response teams are still surveying the damage and knocking on doors and reaching out to folks trying to make contact to see who's alive."
Local congressman James Comer, working with rescuers in the ruined town of Mayfield, said the tornado there was the widest ever seen.
"It's the most devastating storm damage I've seen in my entire life. We've had tornadoes that have been the same length as this tornado but we've never had one with the width of this tornado," he said.