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

undergo

ing surgery. Ms Giffords was shot at close range while meeting

constituent

s 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.

On the eve of a referendum on independence for southern Sudan, its leader Salva Kiir has said there's no

alternative

to peaceful coexistence between north and south. He urged the southern Sudanese to make what he called the most vital decision of their lifetime in a peaceful manner.

"At this

juncture

, our message has been repeatedly, publicly declared, and again I would like to

reiterate