The violence prompted Seattle Mayor Mike McGinn to issue an order grant police emergency powers to try to prevent further violence.
"Using the emergency powers of the mayor's office, I'm issuing an order for the limited purpose of giving police the authority to confiscate items that can be used as weapons," McGinn said.
Just before 5 p.m. a police officer was attempting to take a flag pole from one of the protesters, causing officers and several protesters to grapple for control of the flag pole. During the clash, at least one protester was struck with a police baton and began bleeding from the head.
Aerial video showed police carting off at least one person and placing them into a police van. Seattle Police said eight people had been arrested as of late Tuesday evening.
Property damage from the midday riots was extensive. Seattle police say members of the "Black Bloc" broke windows at the Federal courthouse at 3rd Avenue and Marion, Bank of America at 5th Avenue and Olive Way, Wells Fargo Bank at 4th Avenue and Seneca, Homestreet Bank at 6th and University, Niketown, American Apparel and multiple cars at 6th and Pike Street and 5th Avenue and Seneca.
Officers reported recovering homemade incendiary devices made out of toilet paper rolls and fruit juice boxes, and the large crowd disrupted traffic and Metro and school bus service through downtown, with delays of up to 90 minutes reported by late afternoon.
Police given broader powers
McGinn's emergency order stemmed from dozens of black-clad protesters who were using items that looked like flagpoles as weapons. He said his order would enable police to take those items away from people before they are used to cause damage.
Specifically, the order prevents all people from possessing, transporting or transferring any weapon in the area bounded by I-5 on the east, Yesler Way on the south, and on the north by Denny Way out to Puget Sound. It gives police power to take any weapon or implement "perceived or believed to be capable of being used as a weapon, including tire irons, clubs, metal signs, unusually heavy-duty pieces of lumber...and other objects that could be used to inflict bodily harm or damage to property."
McGinn said his action would help protect public safety as protests continued into Tuesday evening.
"My direction to the police is that I expect them to respond to lawbreaking swiftly and aggressively," McGinn said. "The First Amendment uses of 5-foot-long, 3-inch rod sticks is outweighed today by our desire to preserve public safety and confiscate weapons."
By 8 p.m., officers had seized roughly 70 items which they believed could be used as weapons. Among the items were sharpened wooden stakes, metal poles, screw-topped wooden staffs, and a corrugated metal portable barrier with sharp, jagged edges, according to police.
While much smaller in scale, the mayhem was reminiscent of the 1999 World Trade Organization protests in Seattle that caused widespread damage to stores and forced the cancellation of some WTO events.
"We appreciate that the vast majority of people out there are peaceful participants," McGinn said at a City Hall news conference. "What we know from WTO previously is you get a group of people committed to cause damage."
McGinn said many of the most violent protesters early Tuesday afternoon were trying to hide in the larger crowd by shedding their all-black clothes after they'd caused damage with things like rocks, hammers and tire irons.
'They wasted no time'
KOMO News reporter Joel Moreno and his photographer were hit with a paint bomb while covering the march and ensuing riot Tuesday afternoon.
Moreno said about 50 people wearing black were throwing paint at buildings and cars and painting anarchist symbols, "but there were certainly others not dressed in black participating in criminal behavior."
The march began just after 12:30 p.m. with about 200 people and then the group in black inserted itself into the middle of the parade body.
"They wasted no time," Moreno said. "They went about two blocks before they started damaging property."
Moreno said that's when he was hit with a paint bomb, and up ahead he heard glass shatter.
"We turned the corner and saw large storefronts at Wells Fargo smashed in," he said. "We saw a firebomb of some sort at the U.S. Court of Appeals where they went in and bashed the windows."
Moreno said it looks like a firebomb was lobbed inside. "We saw smoke coming from inside the windows."
The entrance to the Niketown store was completely smashed in, with chunks of broken glass littering the sidewalk. Vandals splattered paint across the store and a neighboring business. Police on bicycles moved in and dispersed people, and the entrances were soon closed off with police tape.
Charlone Mayfield, a retired medical industry worker from Seattle, was inside a Verizon Wireless store when she saw the crowd approach. One of the protesters broke off from the group and struck the window as she watched.
"It scared the bejesus out of me," Mayfield said. "He started hitting the window with his baseball bat... I was here when WTO happened, this is really scary."
Warning: This video contains graphic language:
As protestors smashed windows at Niketown, store owners at the nearby American Eagle store blocked their doors while customers were still inside in an effort to keep rioters out.
At the American Apparel store next to Niketown, assistant manager Mia Harrison was folding sweaters when she heard the commotion.
"I decided to go out on the sidewalk, and I saw all the people in black masks running to Niketown and our store. They started to throw smoke bombs and canisters," she said.
The vandals shattered a door and cracked two windows. No one was hurt. "It's pretty sad, almost like someone broke into my house," Harrison said.
Police were using pepper spray, said a Seattlepi.com photographer who was caught in a melee.
'This is a real welcome to Seattle'
The violence eased just after 1 p.m., but parts of Downtown Seattle remained littered with broken glass, painted windows, smashed cars and slashed tires as emergency vehicles wound their way around the downtown core. Nearly every car for an entire city block was damaged in some way.
Tensions mounted again in the evening as additional protests got under way.
One of those caught in the violence along Sixth Avenue was a tourist from Vancouver B.C. His car's windows were smashed.
"My family came down for a holiday, welcome to the States!" he said. "They (protestors) were just going to town on (Niketown windows) and they (nearby cops) weren't doing anything."
"I don't know why people want pictures of my car. I don't know why they have to mouth off to me and tell me to go back to Canada," he said. "This is a real welcome to Seattle"
The rioters are separate from a peaceful protest and rally that has been under way at the Westlake Center.
Traditionally, May Day honors labor and workers' rights. In Seattle, it drew hundreds of demonstrators for immigration rights and from the Occupy movement, with many converging on a park near downtown for rallies and music.
At 5 p.m., a May Day march starts from a church in the Central District and will go to Wells Fargo's main downtown headquarters as it closes for the day, with frustrations about how the bank treats immigrants and immigration issues.
Police are asking any people or businesses who had their property vandalized should call the Seattle Police non-emergency line at (206) 625-5011.