Gabrielle Giffords and Mark Kelly on stopping gun violence

"Pam and I are praying for everyone involved in last night's mass shooting in Las Vegas".

Giffords who was at a meet-and-greet in 2011 outside a Tucson supermarket when a lone gunman opened fire, killing six and wounding 13, expressed her support for the Vegas victims.

In a statement released before the event, Giffords said, "I know this feeling of heartbreak and horror too well". Democrats have introduced a variety of gun control bills in recent General Assembly sessions, but the Republican-controlled legislature routinely blocks efforts to add new restrictions on the purchase and possession of firearms.

Giffords has always been an advocate for gun control; she and her husband Mark Kelly, a retired American astronaut, launched a political action committee called Americans for Responsible Solutions in January 2013.

"The nation's counting on you", Giffords declared, with a fist extended toward the Capitol.

"We can accept gun violence as simply the cost of living in America, or we can choose courage", Kelly said.

"Awful, bad scene in Las Vegas", Flake said in a tweet Monday morning.

Kelly is calling for a commission to work on solutions to gun violence. "But they are not enough", Kelly said.

Giffords and Kelly were also expected to respond to the shooting on Capitol Hill on Monday afternoon. In its August endorsements, the NRA's Political Victory Fund called Gillespie "a strong supporter of our constitutional rights who will stand up to Michael Bloomberg and his out-of-state gun control groups".

Connecticut Sen. Richard Blumenthal said the Las Vegas shooting shows that, "the time for hand-wringing and soul-searching is over". "None of this ends unless we do something to stop it". "What we need now is a federal system so we're not left with a patchwork of laws across the country".

"What Congress can do - what Congress must do - is pass laws that keep our citizens safe", Minority Leader Chuck Schumer of NY said on the Senate floor.

Scalise, a Louisiana Republican, returned to the Capitol last week after he was shot and critically wounded in June as he and fellow Republicans practiced for a congressional baseball game.

The mayor of Orlando, Fla., which had been the site of the country's deadliest mass shooting before the Las Vegas rampage, reached out on Twitter to offer his condolences. He said the FBI and the Department of Homeland Security are working with Las Vegas police on the investigation.