After one May Day march ended peacefully, a second evening rally escalated into violence and led to the injury of eight officers and the arrest of 17 demonstrators.
Among the crowd that descended from Seattle Central Community College on Capitol Hill were anarchists.
On the Puget Sound Anarchists website, a “day after strategy” was posted early Thursday regarding May Day activities.
A post called a "Cautionary note for rioters" said protesters should throw out the clothes they wore Wednesday night to avoid getting caught.
That article posted at 2:55 a.m. Thursday also said, "...do not keep any other instrument you used to commit a crime … there are already photos in the media of people breaking windows with visible, recognizable implements. Ditch those tools before they become evidence against you."
At one point, when officers were given the order to clear the street, police formed a line and marched forward, chanting: "Move back! Move back! Move back!”
Seattle police were trying to move the group along quickly, so demonstrators wouldn’t have much time to vandalize cars or buildings, but the plan seemed to incite the crowd even more, and suddenly the protesters started gathering in smaller groups around police.
"The crowd surged around several officers who were on foot. Those officers felt their safety was in danger, so they deployed what we call a blast ball. That created some distance and we were able to then coordinate a response to the crowd,” said Seattle police Capt. Chris Fowler. See video of crowd turning angry
Eventually, officers used flash grenades, pepper spray and tear gas to disperse the crowds.
"At that point they started to throw the rocks and bottles, which is obviously a crime and safety and we had a lot of citizens downtown in the afternoon, so we had to take some action,” said Fowler.
Eight officers were injured in the protests and 17 demonstrators were arrested. See video of protester being taken into custody
Some of the weapons used by the protesters against officers were bottles, a hammer, flares and chunks of asphalt.
One female officer was hit in the knee with one of those chunks. Other officers suffered bruises and scrapes.
“Clearly their intent was to confront us and prevent us from making the necessary arrests,” said Fowler.
Some demonstrators said police overreacted, but Seattle Mayor Mike McGinn is defending their response.
"If there was illegal behavior, criminal behavior, violent behavior, for reasons of public safety, the police intended to act, but to use their discretion and judgment, but ultimately to act and maintain order. And I believe that's what they did here,” said McGinn.
On Thursday morning, the City Attorney’s Office charged six of those who were arrested and then held overnight in the King County Jail. Sebastian Harris, 21, and Gregory Husted, 22, were charged with obstructing an officer and resisting arrest, Bryanna Stader, 27, and Justin Gonzalez, 25 were charged with obstructing an officer, 44-year-old Paul Novasky was charged with obstructing an officer, resisting arrest and failure to disperse, and Devin Baum, 20, was charged with property damage and obstructing an officer.
Police said three others who were arrested posted bail overnight and will be considered for charges later.
Meanwhile, after the melee ended, people started cleaning up almost immediately.
Some of the worst damage from the disturbance was at a Walgreens on Capitol Hill where the glass doors were smashed out.
Shortly after midnight, a KIRO 7 crew found workers doing temporary repairs, cutting two by fours and plywood to fill the space left by the broken glass.
But the bad taste caused by the vandalism was still left behind.
"I think it's ridiculous, and I think it's asinine, with technology these days I think there is a lot more that people could do, and be productive instead of destructive,” glass repairman Sean Thornton.
KIRO 7 News also spotted newspapers scattered around some vending machines that marchers had used earlier to try to barricade the street.
Some crews started cleaning up immediately and then parks and recreation workers started in the downtown parks at 4 a.m. and the "clean team ambassadors" began to collect debris downtown.