Rescue crews on Sunday searched through rubble for survivors a day after tornadoes tore across the United States killing at least 22 people and shattering homes and businesses, officials said.

US President George W. Bush called it a "sad day" for devastated communities in the states of Missouri, Oklahoma and Georgia and promised emergency federal aid.

Missouri's department of emergency management said 14 people were confirmed dead in the state, with scores more injured.

"We are still conducting some search and rescue today," department spokeswoman Susie Stonner told AFP, adding that some of the injured were "in hospital in critical condition."

Numerous tornadoes touched down in Oklahoma late Saturday as the storms ripped across the state at 35-45 miles per hour (55-70 kmh), killing seven in the area near the town of Picher, the Oklahoma department of emergency management said. Some 150 people were injured.

Fierce winds ripped roofs off houses, and other homes were thrashed to kindling as the storms downed power lines, utility poles and trees.

"In some cases, only a home's concrete slab remains," Oklahoma authorities said in a statement.

The American Red Cross has opened shelters for those affected by the storms in Oklahoma and Missouri.

Oklahoma Governor Brad Henry declared a state of emergency in the disaster area and planned to visit it later Sunday, while National Guard troops were called to shut off access to Picher.

"We will get through this pulling together and working together as Oklahomans, making sure our neighbors have what they need," Henry was quoted by the Oklahoman newspaper as saying.

The state said that about 6,300 homes and businesses were without electricity, including 3,000 near Tulsa.

Bush called it "a sad day for those who lost their lives in Oklahoma and Missouri and Georgia because of the tornadoes."

Speaking in Waco, Texas the day after his daughter Jenna's wedding on the family ranch, he said: "We send our prayers to those who lost their lives and the families of those who lost their lives, and the federal government will be moving hard to help."

Bush later called Henry as well as governors Sonny Perdue of Georgia and Matt Blunt of Missouri to offer whatever federal assistance they needed, according to White House officials.

The storms barrelled eastward and killed one person and damaged hundreds of homes in the Southeastern state of Georgia in the early morning hours of Sunday, the state's emergency management agency said.

Perdue declared a state of emergency for six counties hardest hit by severe thunderstorms, hail and tornadoes in central Georgia.

The small town of Kite, with some 1,000 residents, was devastated.

"From what I understand it has been completely destroyed," said agency spokeswoman Lisa Janak.

"Many roads are still blocked and impassable," she said. "They're having problems with trees in the road, so these are very preliminary estimates, but the town of Kite sustained significant, significant damage."

Some 18,000 residents were without power in the state, Georgia Power told the Atlanta Journal Constitution.

In February, a string of storms brought rare winter tornadoes to the Southern states of Tennessee, Arkansas, Kentucky and Alabama, killing 55 and injuring hundreds.