Updated: Jan. 9, 11:49 a.m.

President Barack Obama said Rep. Gabrielle Giffords is “battling for her life” after a gunman shot her in the head and killed six others in a Tucson, Ariz., shooting Saturday morning.

“We are going to get to the bottom of this and we’re going to get through this,” Obama said during brief remarks from the White House.

The president said he asked FBI Director Robert Mueller to travel to Arizona to personally oversee the investigation. The Democratic lawmaker was shot while hosting a constituent event in her district and remains in critical condition; the surgeon overseeing her care said at a separate press event that he is “very optimistic” about her recovery. Among those killed were federal judge John Roll, who Obama noted had “served America’s legal system for almost 40 years” and a 9-year-old girl.

The president called Giffords “a friend of mine” and an “extraordinary public servant.” The fact that she was attacked while holding an event for constituents “is why this is more than tragedy for those involved; it is a tragedy for Arizona and a tragedy for our entire country,” he said.

The White House indicated that Obama was notified of the incident by Deputy National Security Adviser John Brennan and Deputy Chief of Staff Jim Messina just after 1:20 p.m. Eastern time.

The president was later briefed by Mueller, along with other senior White House officials including Homeland Security Secretary Janet Napolitano, Attorney General Eric Holder, White House Chief of Staff William Daley, Legislative Affairs Director Phil Schiliro, Brennan and Messina.

Around 3 p.m., Obama also put out calls to several public officials, including Speaker John Boehner (R-Ohio), House Majority Leader Eric Cantor (R-Va.), House Minority Leader Nancy Pelosi (D-Calif.), House Minority Whip Steny Hoyer (D-Md.), Assistant Democratic Leader James Clyburn (S.C.), Rep. Ed Pastor (D-Ariz.) and Arizona Gov. Jan Brewer (R).

The president also called Giffords’ husband and left a message.