At least two tornadoes battered parts of the southern US' Arkansas state, causing "catastrophic" damage in the state's capital city Little Rock, according to the US National Weather Service.
At least one person was hospitalised in critical condition after severe storms moved through central Arkansas, said the Office of Emergency Management in Pulaski County, which includes Little Rock.
Large trees were uprooted, rooftops smashed, buildings severely damaged, and even 18-wheelers blown over, Xinhua news agency reported, citing images posted online.
Members of the Little Rock National Weather Service were also forced to evacuate.
Authorities estimated there were at least 600 injuries so far, and Little Rock police were transporting people to hospitals as there were not enough ambulances to respond, according to local media outlet KTHV.
At least two tornadoes have been confirmed so far. Little Rock's Fire Department said on social media that heavy damage was caused and there was debris in the western end of the city.
As of 4:00 p.m. local time, nearly 75,000 customers were without power across the state, according to PowerOutage.us.
The threat of dangerous severe storms, including tornadoes, will last into early Saturday, meteorologists said.