Seattle authorities have opened an investigation into a pair of viral videos that appear to show the city’s police officers tripping over their own bicycles and using the incidents to arrest people nearby.

The videos, both filmed at or near a protest earlier this month, have racked up millions of views on Twitter. In one, an officer appears to trip over his bike and stumble toward a line of protesters, who had been backing away. Suddenly face-to-face with the protesters, the officer grabs one, wrestling him down. In another video from nearby, an officer riding a bicycle on a sidewalk bumps into a man walking away from him. That officer and another push the man against a window and arrest him while an officer accuses the man of “fighting back.”

Seattle’s Office of Police Accountability is reviewing the incidents.

“We are aware of community concerns regarding arrests during a demonstration,” Seattle Police Chief Carmen Best said in a statement. “I sent this matter to the Office of Police Accountability, and I look forward to the conclusion of their investigation. As always, we remain committed to constitutional policing, supporting First Amendment rights for all.”

The videos highlight the often-tense relationship between police and activists in the Pacific Northwest, where far-right groups and their opponents have frequently clashed in the streets. Both videos were shot on Dec. 7, during a pro-Trump “Mega MAGA” march. The event drew a small crowd from far-right groups like “three-percent” militias and the hate group the Proud Boys, according to Twitter user @JamesonJaymie, a citizen journalist who filmed much of the event.

As with other right-wing rallies, the event drew a separate group of counter-protesters, ranging from black-clad anti-fascists to a “sparkle orchestra” that encouraged people to drown out the pro-Trump crowd with trumpets and kitchen utensils. And as with similar rallies in Portland, Oregon, demonstrators on the left accused police of cracking down disproportionately on the anti-Trump protesters.

They say the pair of bicycle incidents supports their case.

“The Proud Boys were allowed free rein of downtown and anywhere they tried to go police violently cleared the way. Un-housed bystanders and protesters both got caught up in their tactics,” Jameson, who filmed both incidents, told The Daily Beast. The incidents took place within approximately 10 minutes of each other.

In one of the videos, police walking with bicycles advance toward a retreating line of anti-Trump demonstrators. One officer trips over his bike and stumbles into the protestors. Rather than return to his bike, the officer grabs the closest protester, although the man had not made any move toward him. When another protester tries to pull the first man free, officers surround both of them and wrestle them toward the ground.

In a second video, captured from multiple angles by Jameson and by researcher Jerry Savage, police riding on a sidewalk bumped into a man in a red backpack from behind. Several officers surround the man and forcibly arrest him against a building.

“I saw nothing at all that the man did to justify the arrest,” Savage told The Daily Beast.

Jameson said the man had been present at the protests, but that he was separated from the group. In Savage’s video of the same incident, police can be heard telling the man that he’s under arrest, and shouting that he was “fighting back,” even as multiple officers pinned him against a building.

“Didn’t look like he got pushed to me,” Savage called to the officers in the video. “My camera doesn’t see it.”