A series of powerful tornadoes tore across the United States last night, killing at least 21 people.

Susie Stonner, spokeswoman for the Missouri department of emergency management, said there were 13 confirmed dead in her state.

Numerous tornadoes touched down in the evening hours as the storms ripped across Oklahoma at 55-70km/h, killing seven in the area near Picher, Oklahoma.

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

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

National Guard troops were called to shut off access to Picher. The state said that about 6,300 homes and businesses were without electric power, including 3,000 near Tulsa.

US President George W Bush said it was ‘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.’

Mr Bush added that he would be ‘in touch with the governors to offer all the federal assistance we can.’