WASHINGTON • Tornadoes ripped through Tennessee, leaving at least 25 people dead, destroying buildings and toppling power lines hours before the southern US state voted in Super Tuesday primaries.

Voting hours were extended due to the devastation the twisters wrought on Tuesday when they touched down shortly after midnight, with rubble strewn across the state capital Nashville.

Residents ran for their lives as their homes came down around them. Tens of thousands lost power to their homes, officials said.

"TAKE COVER NOW! THIS IS AN EXTREMELY DANGEROUS STORM!!!" the National Weather Service tweeted as one tornado tore through an area west of Nashville.

Television broadcasts showed cars piled up, hangars destroyed and what appeared to be dozens of aircraft smashed into each other at Nashville's John C. Tune Airport.

The Nashville Police Department circulated aerial photographs of many buildings missing roofs and homes destroyed - standing next to houses that escaped damage.

"In the hours ahead, we will continue deploying search and rescue teams, opening shelters across the state, and sending emergency personnel to our communities hit hardest," Governor Bill Lee wrote on Twitter.

Mr Lee said late on Tuesday that the death toll had risen to 25 during the day. Among the victims were two people in Nashville killed after being struck by debris, police said.

Mayor John Cooper said around 150 people had been transported to medical facilities while nearly 50 buildings had collapsed in the city, the hub of the United States' country music scene.

The series of severe storms that passed through Tennessee caused major damage to buildings, roads, bridges, utilities and businesses, the Tennessee Emergency Management Agency said.

US President Donald Trump said that he would visit the stricken areas tomorrow.

"We send our love and our prayers of the nation to every family that was affected, and we will get there and we will recover and we will rebuild and we will help them," Mr Trump said.

AGENCE FRANCE-PRESSE