Buffy the dog lies on the floor of the wreckage of her family's home near Racine, Mo., on Sunday. (Mark Schiefelbein/Associated Press)Crews and search dogs searched through piles of debris in three U.S. states on Sunday, looking for victims of tornadoes and storms that rumbled across the region a day earlier and killed at least 23 people.

In Picher, Okla., a town of 800 and one of the worst-hit communities, seven people died and 150 others were injured.

It's estimated the tornado that struck Saturday afternoon was about 1.5 kilometres across at its peak, with maximum winds of 265 km/h.

A 20-block area was destroyed, emergency officials said. Oklahoma Gov. Brad Henry ordered National Guard troops to arrive on Sunday to help with rescue and recovery efforts.

Residents said the tornado created a surreal scene as it tore through the town, overturning cars, damaging dozens of homes and throwing mattresses and twisted metal high into the canopy of trees.

"I swear I could see cars floating," said Herman Hernandez, 68. "And there was a roar, louder and louder."

Some houses were blown off their foundations. Picher police officer George Brown said he has never seen such wreckage.

"I've not seen anything this devastating. It's like a bomb dropped out of the sky and hit, and just destroyed everything in its path," he said.

People wandering streets in a daze

"People were just wandering up and down the streets. Some had blood on them, some were dazed," said Ed Keheley, 65, who helped rescue a woman who had taken shelter in a bathtub.

A Best Western hotel sign was blown a few kilometres before coming to rest against a post. At one home, a basketball hoop planted in concrete had its metal support twisted so the rim hung only about a metre above ground.

Broken glass was strewn around the inside of 30-year-old Michael Richardson's home, but a wrapped Mother's Day gift and a laptop computer were left unscathed on the kitchen counter.

A flag flies over the wreckage of a destroyed home near Racine, Mo., after the area was hit by tornadoes on Saturday night. (Mark Schiefelbein/Associated Press)The National Weather Service sent out a tornado warning at 5:26 p.m., 13 minutes before the tornado hit Picher, said David Jankowski, a National Weather Service meteorologist in Tulsa. Tornado sirens warned residents to take shelter.

The same storm system later moved into southwest Missouri, where tornadoes killed at least 14 people. The storms moved eastward in the early morning hours of Sunday, killing at least two people in Georgia.

As of Sunday afternoon, weather officials had not yet confirmed if any of the Georgia storms produced tornadoes.

In Seneca, Mo., about 30 kilometres southeast of Picher near the Oklahoma state line, crews on Sunday combed farm fields looking for bodies and survivors. Ten of the dead were killed when a twister struck near Seneca. In total, 14 people died in Missouri.

Promises of federal assistance

"The federal government will be moving hard to help," U.S. President George W. Bush said. "I'll be in touch with the governors and offer all of the federal assistance we can."

Susie Stonner, a Missouri emergency management spokeswoman, said it was unclear how many homes were damaged or destroyed. But she said Newton County officials had initial estimates of 50 homes damaged or destroyed there.

The National Weather Service estimated that at least eight tornadoes had been spawned in Oklahoma along six storm tracks, killing seven people.

On Sunday, storms rumbled across Georgia, killing at least two people in Dublin, about 195 kilometres southeast of Atlanta, authorities said. Weather officials had not yet confirmed whether the storms produced any tornadoes.

The two bodies were found in the rubble of a mobile home, said Bryan Rogers, the Laurens County administrator. Two children were also found in the wreckage but they were unharmed, Rogers said.

By Sunday afternoon, Georgia Power officials said about 72,000 residents were without electricity across the state, mostly concentrated in the metro Atlanta area and the Macon area.

With files from the Associated Press