Shot Congresswoman Following 'Simple Commands'
Christina Greene, nine, was among the dead
The US congresswoman shot in the head in Arizona is following simple commands and surgeons say they are cautiously optimistic about her recovery.
Gabrielle Giffordsremains in a critical condition in intensive care after the attack, which left six people dead.
The 40-year-old Democrat was airlifted to hospital after the shooting and underwent emergency surgery. She is now able to communicate and follow commands.
Neurosurgeon Dr Michael Lemole Jr said: "We are very encouraged by that, I am cautiously optimistic.
Christina Greene, nine, was among the dead
Federal judge John Roll and nine-year-old Christina Greene were among those killed in the shooting.
Christina's mother, Roxanna Green, told Fox News: "I can't even put it into words.
I can't express the devastation and hurt, and how we were so robbed of our beautiful princess.
Also killed were Phyllis Schneck, 79, Dorothy Murray, 76, Dorwin Stoddard, 76, and 30-year-old Gabriel Zimmerman.
The shootings took place outside a supermarket where Ms Giffords was meeting constituents.
Police investigating the shooting spree have released an image of a second man they would like to trace.
He was pictured at the scene of the attack in Tucson, Arizona, as officers appealed for the public's help to try to identify him.
The man is described as white, about 40-50 years old, with dark hair and was last seen wearing blue jeans and a dark blue jacket.
Another man, who carried out the shooting, is already in custody after being arrested at the site of the atrocity.
He has been identified by a federal law official as 22-year-old Jared Lee Loughner.
FBI director Robert Mueller said he is expected to be formally charged later and added "no specific threat remains" against other officials after the shooting.
The home Loughner shared with his parents has been searched and a computer has been taken away by officials.
Police said the gunman opened fire at point-blank range using a semi-automatic pistol.
A Tucson fire official said the number of wounded was 13.
Pima County Sheriff Clarence Dupnik said the detained suspect, who was tackled after the shooting and is in custody, has "a troubled past".
US President Barack Obama said: "We don't yet know what provoked this unspeakable act," calling the shooting a "senseless and terrible act of violence.
Sky's US correspondent Greg Milam said Mr Obama has dispatched FBI director Robert Mueller to Arizona to oversee the investigation.
House of Representatives Speaker John Boehner has ordered flags at the US Capitol in Washington lowered to half mast in memory of the victims.
He said the incident was a reminder that public service comes with a risk.
Mr Boehner told reporters: "This inhuman act should not and will not deter us from our calling to represent our constituents and fulfil our oaths of office.
No act, no matter how heinous, must be allowed to stop us from our duty.
Gun violence is common in America, which is periodically rocked by mass shootings, but political shootings are rare.
The shootings followed contentious congressional elections in November.
The polls were marked by heated rhetoric over issues like the Democrat-led drive to overhaul the US healthcare system and immigration reform.
A window in Ms Giffords' office was smashed in March, after Congress passed the healthcare overhaul that had been opposed by Republicans.
The rhetoric is really heated. Not just the calls but the e-mails, the slurs, Ms Giffords told television network MSNBC at the time.
Ms Giffords was hosting a Congress on Your Corner" event when the gunman attacked from about 4ft away, National Public Radio said.
The suspect approached the politician from behind, firing at least 20 shots at her and others in the crowd, MSNBC reported.
In March, Republican Tea Party favourite Sarah Palin released a 'target list' of Democrats she wanted to see unseated in last November's mid-term elections. Mrs Giffords was on the list.
At the time, Mrs Palin drew criticism for telling her followers Don't retreat instead, reload!
Regarded as a rising star in the Democratic Party, Ms Giffords was one of the few Democrats to survive the Republican sweep in "swing" districts in the elections.
Ms Giffords is a moderate who narrowly beat a Tea Party candidate who tried to throw her out of office over her support for the health care law.
Sky News US political commentator Jon-Christopher Bua said: "Today we are saddened to see that words of violence like reload have horrible consequences.
He also predicted increased security for US politicians following the Tucson attack.
Life in Washington and elsewhere for Members of Congress is about to become more challenging as heightened security will be the order of the day.
Sky News Online