FOR JAKE AUCHINCLOSS, the first days in office as a new member of Congress have felt the same as they likely did for hundreds of lawmakers before him — momentous and awe-inspiring. Now add to that a very different adjective: chilling. 

The newest member of the state’s congressional delegation was sheltering in place with his staff in his office on Wednesday afternoon as the nation witnessed a scene once unimaginable in the world’s most robust democracy: An armed invasion of the Capitol by mobs of supporters of the current president seeking to reverse the outcome of a fairly conducted presidential election.

“It’s a dark day for democracy,” Auchincloss said by phone at about 3:30 from the Longworth House Office Building, where he and his staff had been ordered to shelter in place by the US Capitol Police.

There were reports of an armed standoff at the doors to the House chamber between police and those leading what can only be termed an attempted insurrection. Auchincloss said a demonstrator had entered the Senate chamber. 

The Associated Press reported one person was shot during the melee with President Trump supporters. NBC News reported later that the woman, who was in critical condition, died. 

The Capitol was locked down and Senate and House proceedings were immediately called into recess. Senators and House members were being moved to secure locations. 

Trump, who has spent weeks feeding the anger of his supporters by advancing groundless claims of election fraud, spoke earlier in the day to thousands of protesters who had come to Washington to demonstrate against today’s congressional session where the electoral votes of the states will be accepted, the final step in the process sealing the election of Joe Biden and Kamala Harris as president and vice president. 

Auchincloss, a Newton Democrat elected in November to the Fourth Congressional District seat previously held by Joe Kennedy, said Trump is directly responsible for the mob attack on the Capitol building.

“This is what it looks like when Donald Trump has a temper tantrum,” he said. “This is the manifestation of it. It is emanating from the cult of personality he has built. It’s pathetic and it’s damaging, but it’s not going to win the day. This is not going to destroy the core institutions of our democracy.”

Rep. Seth Moulton, on Twitter, called on officials in Trump’s administration to use their constitutional authority to remove him from office. 

“Trump is directly responsible for this insurrection and violence,” said Moulton, a Democrat from Salem. “He needs to be removed from office immediately. It is the Constitutional responsibility of Vice President Pence and the cabinet to exercise the power granted them by the 25th amendment.” 

“This is anarchy,” wrote Moulton. “This is an attempted coup. And it’s happening in America because of lawless lawmakers. That they are colleagues makes me embarrassed and sad for our country.” 

“We are being told to shelter in place not because of a foreign terrorist attack but because of a domestic coup attempt,” he said in a Twitter post. “I expected this as a US Marine in Iraq. I never imagined it as a US Congressman in America.” Moulton served four tours of duty in Iraq. 

Other members of the Massachusetts congressional delegation began posting reactions as they were shepherded to other locations by Capitol police.  

Rep. Jim McGovern also called the security break a “terrorist attack,” adding that he is in a secure location. 

“When the situation is under control, we will resume proceedings on the House Floor. America’s democracy will never be deterred. Not today. Not ever,” he wrote on Twitter.  

Sen. Ed Markey posted shortly before 3 pm that he and his staff are safe and sheltering in place.   

Rep. Katherine Clark, the assistant House speaker, called the unfolding situation “an attack on America” online.  

“This dark moment is the culmination of everything Trump has been promoting. Praying for an end of the violence and safety for everyone, and the preservation of our democracy. This must stop,” she said.  

Auchincloss said he was making plans to head to the House chamber to vote against efforts to block acceptance of the electoral vote tally in states Trump lost when the protests turned into an armed invasion of the Capitol. 

“In the last 90 minutes it’s been clear that the protests hit a tipping point in terms of massing and also the menacing nature of them,” Auchincloss said. “These group protests tend to self-catalyze in their destructive behavior, and that’s what’s happening.” 

Asked whether Capitol police should have been better prepared for the events, with weeks of warning that Trump protesters were heading to Washington today, Auchincloss said it’s too early to draw conclusions. 

“I’ll be interested to see a debrief from the Capitol Police and the mayor of Washington,” he said. “Until we have the facts, I don’t think it’s fair for me to weigh in.” 

Trump told supporters at the rally earlier Wednesday to demand that Congress investigate allegations of election fraud.   

“You’ll never take back our country with weakness. You have to show strength and you have to be strong,” he said.  

After rioters breached the doors of the US Capitol, his messaging shifted. Trump tweeted that he’s asking for everyone to remain peaceful. ” No violence! Remember, WE are the Party of Law & Order – respect the Law and our great men and women in Blue. Thank you!”  

Every member of the Massachusetts delegation, except for Rep. Stephen Lynch, is calling for Trump’s cabinet to invoke the 25th amendment to remove the president from office. Lawmakers said Trump incited the rioters.

“Donald J. Trump should immediately be impeached by the House of Representatives & removed from office by the United States Senate as soon as Congress reconvenes. This is dangerous & unacceptable,” wrote Rep. Ayanna Pressley online.