A gunman shot Representative Gabrielle Giffords, Federal District Judge John Roll, and more than a dozen bystanders at a public event in Tuscon, Arizona on Saturday morning. 

At least five people have died, according to multiple media accounts, including Judge Roll and a nine-year-old girl. But the exact number is not clear. Several victims are at hospitals, in critical condition and undergoing treatment.

Giffords survived the attack and, according to a physician from University Medical Center at Tuscon, is recovering from neurosurgery.  The doctor said that she was shot "through the brain" but that he is "optimistic" about her condition and that she had been responsive to commands.

President Obama, who addressed the nation from the White House, said she is "fighting for her life."

Police have said that a suspect, whom the Associated Press has identified as 22-year-old Jared Laughner, is in custody. 

So far the accounts paint a fairly consistent picture of what transpired. Giffords, a Blue Dog Democrat who just won her third term, was at a Safeway hosting her first town hall since re-election. At some point, a gunman approached her and shot her once, in the head and at point blank range. 

It's not clear when the gunman shot the other victims. Several witnesses reported hearing a rapid succession of about fifteen shots. More recent accounts quote witnesses recalling nearly twenty shots. Several media reports say the gunman used a Glock 9 mm semi-automatic pistol and police say it had an extended magazine that would hold extra bullets.

Nothing has been said about the gunman's possible motives. 

On at least two previous occasions, Gifford's staff were concerned about violence. At one town hall event event, aides contacted police after an attendee dropped a gun, according to an account in the Huffington Post. And in March, 2010, a few hours after Gifford voted in favor of the Affordable Care Act, somebody smashed the front window of her district office.

Judge Roll had been the subject of death threats following a decision in which he allowed a lawsuit against a rancher, brought by illegal immigrants, to go forward. 

Last updated at 5:45 p.m.