The worst mass shooting in modern American history was met with immediate calls for action on gun control Monday from some Democratic lawmakers.

Sen. Chris Murphy, D-Conn., demanded Congress "get off its ass and do something."

"This must stop," Murphy said. "It is positively infuriating that my colleagues in Congress are so afraid of the gun industry that they pretend there aren't public policy responses to this epidemic."

He added, "The thoughts and prayers of politicians are cruelly hollow if they are paired with continued legislative indifference. It's time for Congress to get off its ass and do something."

While most of their colleagues on both sides of the aisle stuck to sending condolences to victims and their families, some other Democrats also expressed outrage that Congress has not done more to restrict access to deadly firearms five years after the Sandy Hook Elementary School shooting in Newtown.

Former Vice president Joe Biden, who led an Obama administration task force on gun violence, said there was "no excuse for inaction."

There was still little information that had been made public about the type of weapons the Vegas gunman used and how he acquired the weapons. Police say the shooting left 50 dead and sent more than 400 to the hospital.

Connecticut was the catalyst for the gun control debate after the Sandy Hook massacre, and the state’s other Democratic senator, Richard Blumenthal, said he was "furious" at Congress' inaction.

"It has been barely a year since what was previously the largest mass shooting in American history — the deadly attack at Pulse nightclub," Blumenthal said in a statement of the 2016 massacre in Orlando. "In the interim, thousands more have been lost to the daily, ruthless toll of gun violence. Still, Congress refuses to act. I am more than frustrated, I am furious."

Rep. Jim Himes, D-Conn., expressed little hope that Congress would respond any differently this time.

Congress is currently debating two major laws to loosen gun restrictions.

One bill would make permits to carry concealed weapons valid across state lines, effectively undermining states that have chosen to enact stricter gun laws. The other would make it easier for people to buy silencers, which advocates say would limit hearing damage for hunters and recreational shooters, but which opponents say could make it harder for police to locate gunmen during an active shooting.

Hillary Clinton, the former Democratic presidential nominee, urged supporters to "stand up to the NRA" on that bill.

Michael Bloomberg, the former New York City mayor and leading gun control advocate, echoed the call for action.

The political discussion after mass shootings tends to follow a familiar script, with Democrats calling for gun restrictions and Republicans responding by saying Democrats are too quick to politicize tragedies and defending gun rights.

But after years of inaction on guns, Democrats on Monday seemed to have run out of patience.

Sen. Elizabeth Warren, D-Mass., said on Twitter that sending thoughts are prayers is "NOT enough" and that Congress needs to discuss ways to stop gun violence "NOW."

Sen. Sen Sheldon Whitehouse, D-R.I, asked, "How many lives must be lost before we act?" And Sen. Cory Booker, D-N.J., said his colleagues need to do more than express sympathy.

Sen. Tim Kaine, D-Va., the party's former vice presidential nominee and a moderate up for reelection next year, lamented, "We suffer these horrific events repeatedly and do nothing to stop them. We must do better."

The public has been divided on gun control, largely along party lines, according to an August NBC News/Wall Street Journal poll. Half of respondents said they were concerned the government will go too far in restricting the rights, while 45 percent said they were worried the government will not do enough.

And while some gun restrictions, like universal background checks, tend to poll overwhelmingly favorably, the voters who care most about guns and tend to be those opposed to new restrictions, and they vote, volunteer, and donate to politicians who support that view.