For almost two weeks, the Capitol has witnessed a slow-motion version of some of the most terrifying days inside Congress.

The atmosphere boiled over with anger as legislative gridlock helped fuel the precipitous drops in financial markets at levels that dwarfed the Wall Street panic after a failed House vote on a 2008 rescue package. Lawmakers grew more bitter as negotiations dragged on over a $2 trillion relief package as the U.S. coronavirus death toll soared past 600 and climbed higher, with some experts warning it will exceed the 3,000 lives lost in the 2001 terrorist attacks.

Yet what truly distinguishes this crisis from those others is fear, the fear inside the Capitol hallways. Three lawmakers and several aides have now tested positive for the disease.

They are racing against the clock to pass an emergency package to try to save hospitals from the wave of cases and to provide a floor for a cratering economy — and they are racing a second clock they cannot see, the spreading virus inside the Capitol.

“It’s in the building. It’s sort of insidious. It’s here, but we can’t see it,” said Sen. Rob Portman (R-Ohio).

Portman recalled how on Sept. 11, 2001, lawmakers raced out of the building in a confused state, learning later that a hijacked plane was likely headed to the Capitol. But hours later, they realized they were safe, returning to the Capitol steps that night in a show of defiance to sing “God Bless America.”

This week, whenever Congress passes the coronavirus legislation, lawmakers will leave the Capitol for an unknown length of time.

Sen. Christopher A. Coons (D-Del.) described the “push and pull” of wanting to get this legislation done right but also the need to get home to family, friends and the community leaders who have spent the past week on the phone describing a looming disaster.

“Feeling as if there is an invasion or a disaster about to really hit,” Coons said.

That powder keg of tension blew up on the Senate floor Monday as normally mild-mannered senators lobbed allegations at one another over whose fault it was that the rescue plan had not been approved yet and that they were still there debating it.

When Senate Minority Leader Charles E. Schumer (D-N.Y.) blocked the right of Sen. Susan Collins (R-Maine) to speak, the floor erupted. Curses could be heard from the Republican side of the floor.

Any sense of social distancing disappeared, as 13 Republicans crowded their side of the floor. Collins walked to within a foot of Schumer, raised her finger and repeatedly pointed at him, saying, “This is appalling!”

The rest of Monday and Tuesday unfolded like that in public, as a Senate that for almost a decade has withered away in terms of grand debate and compromise saw its members turn on each other. All the pent-up frustration boiled over.

Portman, who served as a GOP negotiator on the unemployment insurance provisions of the package, said he got “fired up” because he is taking these negotiations more personally than any crisis of this century.

“Unlike the financial crisis, or even 9/11, this is affecting everybody and everything. And we all know people who are unemployed and we all know people who are sick. I know someone who died. It’s very personal,” he explained.

It was also the first time senators were on the floor together since Sen. Rand Paul (R-Ky.) tested positive for coronavirus, which followed a six-day journey from when he got tested March 16 until he got his results Sunday.

Any of them could have the deadly virus, and they all know it now.

That wasn’t the case after the 2001 attacks. The days that followed were frantic, with Congress setting off on a wave of recovery for New York and Washington and retribution for America’s new enemy.

Even when two anthrax-laced letters were sent to two senators in October 2001, they were handled by staff and mail service workers, thus never posing an imminent danger to lawmakers.

There were occasional pell-mell evacuations that occurred because of suspected bombs or plane mishaps — perhaps none more terrifying than the arrival service for former president Ronald Reagan’s lying-in-state honors after his 2004 death.

The Kentucky governor’s plane had a communication malfunction as it approached Washington, triggering a Capitol evacuation. The police screamed at visitors and staff, “Plane, three minutes out!”

An F-16 nearly shot the aircraft down but quickly determined it was not a terrorist attack, ending the threat in a half-hour.

The past two weeks have been those 30 minutes of that day, playing on a recurring loop, mixed in with the same slow-motion 2008 meltdown on Wall Street.

On a Thursday night in September 2008, the Bush administration’s top advisers and Ben Bernanke, then the chairman of the Federal Reserve, showed up in current House Speaker Nancy Pelosi’s office for a bipartisan congressional leadership meeting.

They asked for $700 billion, by Monday.

The leaders blew that deadline, just as this era’s congressional leadership missed Treasury Secretary Steven Mnuchin’s Monday deadline for a package almost three times as big. For two weeks in the fall of 2008, House and Senate leaders haggled over how to structure a bailout for Wall Street firms that had placed their own bad bets, including a failed vote that led to a nearly 800-point drop in the Dow.

Senators and Mnuchin expressed growing confidence throughout Tuesday that they were on the cusp of a massive deal that would probably pass the Senate on Wednesday and, as Pelosi has requested, a unanimous consent vote in the House later that day.

That’s because huge numbers of House members do not want to board planes and travel across the country to return to a chamber with more than 430 members to vote, fearful that they could spread the virus or catch it in transit.

All of which makes this crisis unlike anything congressional veterans have seen. Nerves are frayed, ranging from gallows humor to downright tense moments.

“Keep your distance,” Sen. Deb Fischer (R-Neb.) joked to Sen. John Barrasso (R-Wyo.), coming off an elevator Monday.

“We’re gonna want you all to step back a little,” Sen. Joe Manchin III (D-W.Va.) told reporters Tuesday, as they were inside the six-foot zone health experts recommend.

At least they made progress on legislation, to put aside “the bickering” and pass a massive bill, Coons said. “Pass it and then get home.”

For how long? “We have no idea.”