CNN — WASHINGTON (CNN) -- The slogging efforts to resolve the federal government's budget crisis ground to a halt Thursday as shots rang out around the Capitol, forcing legislators and their staffs to call off any business and shelter in place.
The gunfire -- first reported around 2 p.m. ET -- prompted a lockdown of Capitol Hill buildings, as well as of the nearby Supreme Court. It also caused debate on the House and Senate floors to cease suddenly, with people soon thereafter told they could not leave, nor could anyone else come in. The lockdown was lifted around 3 p.m.
The incident comes on the third day of the government shutdown, which came after the two chambers of Congress failed to agree on a budget plan to send to President Barack Obama.
Earlier Thursday, Obama directly challenged House Speaker John Boehner to end the shutdown by bringing up a spending plan already approved by the Democratic-led Senate. Boehner, however, has steadfastly resisted other pleas in the past. Instead he has insisted that the Senate reconcile its plan with that of the Republican-led House, which includes provisions targeting the president's signature health care reform, the Affordable Care Act.
The president gave his latest pitch one day after these two men, as well as other Congressional leaders, met face-to-face for the first time since the budget impasse put 800,000 workers at risk of furloughs and caused increasing concerns over direct and collateral economic harm.
Back on the attack
In a campaign style-speech earlier Thursday in Rockville, Maryland, Obama was back on the attack against what he called the "reckless" strategy by Republicans that he said imperiled the nation's economic recovery from recession.
He insisted that the Senate version of a short-term spending plan to fund the government would pass the House with support from Democrats and some Republicans.
"The only thing that is keeping the government shut down, the only thing preventing people from going back to work, and basic research starting back up, and farmers and small business owners, getting their loans -- the only thing that's preventing all that from happening right now today, in the next five minutes, is that Speaker John Boehner won't even let the bill get a yes-or-no vote because he doesn't want to anger the extremists in his party," Obama said.
A conservative GOP wing has demanded that any spending measure include provisions to dismantle or defund Obamacare, the president's signature health care reforms passed by Democrats in 2010 and upheld by the Supreme Court last year.
The anti-Obamacare provisions caused the impasse, with Obama and Democrats refusing to link partisan demands to any plan to keep the government funded.
Cantor: GOP should stand its ground
House Majority Leader Eric Cantor urged his GOP colleagues to maintain their stand, issuing a memo that called the position of Obama and Democrats "untenable."
House Republicans would continue passing piecemeal funding measures for popular programs such as veterans affairs, national parks and medical research to keep up pressure on Senate Democrats who refuse to consider such measures in the ongoing stalemate, Cantor's memo said.
"While no one can predict with certainty how the current shutdown will be resolved, I am confident that if we keep advancing commonsense solutions to the problems created by the shutdown that Senate Democrats and President Obama will eventually agree to meaningful discussions that would allow us to ultimately resolve this impasse," Cantor said in the memo that a GOP source made available to CNN.
A conversation between two conservative GOP senators showed Republicans think they can win the debate. In the comments caught by live microphone, tea party backed Sen. Rand Paul tells his Kentucky GOP colleague, Minority Leader Mitch McConnell, that continuing to hammer Democrats for refusing to consider GOP proposals would eventually succeed.
Proposal from moderates
Meanwhile, two moderate House members -- one Republican and one Democrat -- proposed a compromise Thursday that would fund the government for six months while eliminating a tax on medical devices in the health care reforms.
Senate Democrats quickly rejected the idea because it would link the health care reform provision to the need to fund the government now while extending deep mandatory budget cuts they oppose for half of the new fiscal year.
Instead, Obama and Democrats want to negotiate a broader budget deal that could include tax reforms and other matters, but only after the government is reopened through passage of a "clean" short-term spending plan with no anti-Obamacare provisions.
In his speech, Obama urged Congress to "pass a budget that funds our government with no partisan strings attached." He also called on Republicans to support raising the federal debt ceiling, which must be increased by October 17 so that the United States does not default on its obligations.
"As reckless as a government shutdown is, an economic shutdown that results from default would be dramatically worse," Obama said, noting that Social Security checks and disability benefits would be affected.
"There will be no negotiations over this," the president said.
Obama was speaking to workers at at M. Luis Construction, in part to highlight impacts of the shutdown on small businesses. Many are suffering this week because some customers and clients -- idle federal workers or agencies -- aren't doing business.