Seattle police clashed with crowds Friday evening as a May Day march moved through the streets and left damage in its wake.
The demonstrations began as a peaceful immigration rally in downtown, but as the rally ended, an anti-capitalist march began moving through the streets.
According to the Seattle Police Department, 15 people were arrested during the protests. Three police officers also were injured, two of whom had to be transported to the hospital.
After violence erupted, the Seattle Police Department called the demonstration a "riot."
"This is no longer demonstration management, this has turned into a riot" -Captain Chris Fowler. #MayDaySea
The police department also said on Twitter that protesters threw an explosive device.
Images from the protest showed people moving through the streets and in some cases damaging buildings and vehicles.
Protestors bashed out the window of our livetruck #SeaMayDay
Shayne Butts, carrying SKS rifle, here to "protect constitutional rights and freedoms for everyone" at #SeaMayDay
Students at Seattle Central, here's a little something to remember the protesters. #MayDaySeattle
#MayDaySea Broken windows at Urban Outfitters on East Harrison and Broadway.
Police responded in force, with armored officers using bicycles to control the crowds. Images also showed flash bangs going off near protesters.
Police using flash bang grenades to corral protesters on Broadway in Capitol Hill #MayDaySea
#SeaMayDay more flash bangs and pepper gas. Air is tinged with it.
Many protesters, as well as at least one journalist, appeared to sustain injuries.
Photographer Scott Lum got hit after a flash bang went off. #MayDaySea
"I was just walking." Protester who got pepper sprayed.
Man icing injury from police flash bang. Hit my ankle too (I'm fine) More: http://t.co/bwDyTsQjMS #MayDaySea #MayDay
While the protest was organized for May Day, at one point participants chanted that they stood with Baltimore, which has seen massive protests over the death of Freddie Gray.
"Who stands with Baltimore? We stand with Baltimore" #MayDaySea #Video
The Seattle Times reported that as of 9:30 p.m. PT, the protesters had marched to Seattle Central College and were engaged in a standoff with police.
Anarchists light trash cans and sticks in front of Seattle Central #MayDaySea #Video
Standoff at Seattle Central College #MayDaySea protest. Go to http://t.co/mGUw07Lhm7 for details.