Misinformation about the extent of the unrest in Washington, D.C., and false claims about widespread communications outages burgeoned Monday on Twitter, making the #DCblackout hashtag into a nationwide trend on the platform.

Started by an account with just three followers, the hashtag exploded in popularity, generating about half a million tweets in its first nine hours after being created. The thread swelled with untrue claims that authorities had somehow blocked protesters from communicating from their smartphones to crack down on the unrest, which included looting and some fires.

Several Twitter accounts shared images of a major fire burning out of control near the Washington Monument, but others noted that the image appeared to have been copied from the television show “Designated Survivor.”

D.C. Police Chief Peter Newsham said Monday there had been no communications blackout “in any shape or form,” he said. “That’s why I rarely take a lot of the information that I get from social media on its face.”

Chris Rodriguez, the director of the D.C. Homeland Security and Emergency Management Agency, speaking at the same news conference, seemed to confirm Newsham’s statement, saying his office monitors social media for disinformation campaigns and passes any intelligence to federal and local law enforcement.

Twitter said Monday afternoon that it had acted against many accounts using the #DCblackout hashtag.

“We’re taking action proactively on any coordinated attempts to disrupt the public conversation around this issue,” said spokesman Brandon Borrman. “We are actively investigating the hashtag #DCblackout and during that process have already suspended hundreds of spammy accounts that tweeted using the hashtag.”

Days of protests, often organized and shared over social media, have tested the ability of platforms to manage the flow of misinformation, said independent analysts who themselves struggled to keep up with torrents of content.

Sorting among real users, fake users and bots — not to mention truth and falsehood — has proven even more daunting than usual. Social media played a central role in how protests developed, providing an immediate feedback loop of action, reaction and publicity, analysts said.

“It’s an accelerant,” said Claire Wardle, the U.S. director of First Draft, a nonprofit group that combats misinformation. “This is what happens when people are emotive, and they have phones that connect people immediately.”

The #DCblackout hashtag got early support from what appeared to be fake accounts, including several that more commonly tweet about Korean popular music, said Darren Linvill, an assistant professor of communication at Clemson University who studies social media misinformation.

“This is a hashtag that was clearly started by an account that was fake and was pushed by fake accounts,” Linvill said. But content from real accounts using #DCblackout soon surged, including many that challenged claims of a communications blackout in the city.

Protests in downtown Washington and near the White House were widespread Sunday night and into Monday morning. What started as largely peaceful protests over last week’s police killing of George Floyd in Minneapolis deteriorated after dark in the District, with rioters smashing windows, starting fires and overturning vehicles — despite an 11 p.m. curfew.

But the degree of mayhem described by tweets using #DCblackout went far beyond reality. Alarming text was interspersed with shaky videos of confrontations between police and protesters, though it wasn’t clear how many of the images were from Washington, as opposed to other U.S. cities facing unrest.

Joan Donovan, director of the Technology and Social Change Project at the Harvard Kennedy School’s Shorenstein Center on Media, Politics and Public Policy, said that people promoting the hashtag apparently wanted to distract the public from the actual aims of the protesters.

“The controversy about #DCblackout is indicative of serious problems with the design of Twitter’s trends,” she said. “Activists are trying to get the word out that the police attacks against them were dangerous, but the focus is on if there was or was not a blackout. We must pay attention to the voices of those on the ground last night.”

One typical tweet said, “no one from DC has been heard from since 1am. police had silencers on their rifles which do not need to be used with rubber bullets. all signals are jammed. the city is on blackout. the president is hiding in a bunker. what … is going on and where is everyone #dcblackout.”

As the comments on the hashtag grew, others disputed the accounts. One tweet said, “as someone seeing #dcblackout trending, who lives and works in the DC metro area, and who has friends telecommuting into DC … this hashtag looks like misinformation. ‘No social media from DC’ because we were asleep. Stop scaring people #dcsafe.”

But that, too, appeared to be the product of manipulation. Linvill said that exact text appeared in tweets from more than 200 individual accounts, including from people who later disavowed the sentiment, saying they had no direct knowledge of what happened in Washington. The text was retweeted thousands of times.

A separate thread, which also trended on Twitter, featured discussion — much of it obviously fanciful — about what it would take to topple the Washington Monument.