Biden roars back on Super Tuesday

Tornadoes kill 25

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

Voting hours were extended due to the devastation the twisters wrought when they touched down shortly after midnight－rubble was strewed 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.

"It hit so fast, a lot of folks didn't have time to take shelter," Putnam County Mayor Randy Porter said. "Many of these folks were sleeping."

The governor declared an emergency and sent the National Guard to help with search-and-rescue efforts. An unspecified number of people were missing.

The balance of Super Tuesday's battlefield－with Biden winning at least eight states and Sanders four-raised questions about whether the Democratic primary contest would stretch all the way to the July convention or be decided much sooner.

The former vice-president showed strength in the Northeast with a victory in Massachusetts. He won delegate-rich Texas in the Southwest, Minnesota in the upper Midwest and finished on top across the South in Virginia, Alabama, North Carolina, Tennessee and Arkansas－in addition to Oklahoma.

Sanders opened the night as the undisputed Democratic front-runner and was in a position to claim an insurmountable delegate lead. And while he scored the night's biggest delegate-prize in California, he scored just three other decisive victories, winning his home state of Vermont, along with Utah and Colorado.

Agencies, Xinhua and William Hennelly in New York contributed to this story.