This piece may be updated.

Riot police arrested and used tear gas and pepper spray against protesters in the streets of Washington, D.C., on Friday, as crowds blockaded inauguration checkpoints and clashed with law enforcement as well as supporters of newly sworn-in President Donald Trump.

From LGBTQ activists to members of the Black Lives Matter movement to Dakota Access Pipeline opponents to anti-fascists, protesters represented a wide array of concerns and employed multiple tactics. But they were united in their opposition to Trump, whose right-wing agenda they see as a threat.

Thousands of water protectors marching thru streets of DC to say NO to Trump & the GOP's racist, sexist, fascist agenda. #NoDAPL #DisruptJ20 pic.twitter.com/0KTUJT8NKz — Collin Rees (@collinrees) January 20, 2017

For some, the militarized crackdown—which reportedly impacted both protesters and journalists—was a troubling harbinger of what's to come under a Trump administration, as Trump himself has repeatedly emphasized "law and order must be restored."

Trump's America begins with mass arrests, pepper-spray, and brutalized protesters, lawyers, and press here in DC. #disruptj20 #Inauguration — Inaugural Augur (@joe___nelson) January 20, 2017

Washington Post reporter Dalton Bennett thrown to the ground by riot police. pic.twitter.com/4I442QhEqM — Alex Emmons (@AlexanderEmmons) January 20, 2017

Water protectors - Dakota Access Pipeline protesters - clash with cops at entry to parade route @ 14th & F pic.twitter.com/sVaLpyxIJ9 — Alexandra Jaffe (@ajjaffe) January 20, 2017

Protests and blockades begin at #TrumpInauguration Thousands block checkpoints-Police use pepper spray. #disruptj20 #McPhersonSquare pic.twitter.com/0S1RFWWaox SCROLL TO CONTINUE WITH CONTENT Never Miss a Beat. Get our best delivered to your inbox.





— DCMediaGroup (@DCMediaGroup) January 20, 2017

Much of the protest action was being documented under the hashtag #DisruptJ20:

#DisruptJ20 Tweets

The Intercept's Jeremy Scahill was covering the protests live:

In another moment of resistance, six citizen activists stood on their chairs in the middle of Trump's inaugural ceremony, revealing the message "RESIST" across their sweatshirts and reciting the preamble of the Constitution. All six millennial activists—four women and two men—were escorted away by security personnel but not arrested.

"Today we disrupted President Trump's swearing-in ceremony to show the world, and our fellow Americans, that the resistance starts now," said Claire Sandberg with AllofUs. "We will not stand idly by while a political conman flouts our Constitution and basic democratic norms, and pledges to violate the rights and dignity of millions of people on day one. We will fight to protect our families, neighbors, communities, and democracy from Trump's agenda of hate and greed every step of the way, and we will not back down."

Friday's protests came on the heels of anti-Trump demonstrations on Thursday night, some of which were also met with clouds of tear gas and walls of riot police.