WASHINGTON - A series of powerful tornadoes has torn across the US, killing at least 21 people and shattering homes and businesses, officials and media said.Susie Stonner, spokeswoman for the Missouri department of emergency management, said there were 13 confirmed dead in her state as search-and-rescue workers searched for survivors today. ----------------- GALLERY: Tornadoes rip through USA ----------------- Numerous tornadoes touched down in the evening hours yesterday as the storms ripped across Oklahoma at 55-70 km/h, killing seven in the area near Picher, Oklahoma, the state department of emergency management said. About 150 people were injured.The high winds ripped roofs off houses, and other homes were crushed to kindling as the storms downed power lines, utility poles and trees."In some cases, only a home's concrete slab remains," the state 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 today."Our thoughts and prayers are with the people of Picher and all of the other Oklahoma communities that have been impacted by the latest wave of severe weather," Henry told CNN.National Guard troops were called to shut off access to Picher. The state said about 6,300 homes and businesses were without electric power, including 3,000 near Tulsa.US President George W 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 added he would be "in touch with the governors to offer all the federal assistance we can".The storms barrelled eastward and killed one person in the south-eastern state of Georgia in the early morning hours today, that state's emergency management agency said.The small town of Kite, with some 1,000 residents, was apparently devastated."From what I understand it has been completely destroyed," said department spokeswoman Lisa Janak. "It experienced significant damage.""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."Janak could not confirm whether the storm had spawned any tornadoes."The National Weather Service will have to send out a survey team to determine that for sure," she said.About 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. AFP