BBC News with Marion Marshall

A United States congresswoman Gabrielle Giffords has been shot in the head during a public event in Arizona. Initial reports suggested she had been killed, but a hospital spokesman said later that she was still alive and in a critical condition. She's now undergoing surgery. Ms Giffords was shot at close range while meeting constituents outside a supermarket in the city of Tucson. Several other people were also shot. Six are said to have been killed, and 11 wounded. Iain MacKenzie reports from Washington.

Details are still emerging from the town of Tucson, Arizona. Eyewitnesses say one or more gunmen opened fire at Gabrielle Giffords' Congress on the Corner event. Representative Giffords was taken to a local hospital and is understood to be undergoing surgery. Police in Tucson have taken one man into custody. Gabrielle Giffords has served as a member of Congress since 2007 and is regarded as a rising star in Barack Obama's Democratic Party.