Last Updated 8:46 a.m. ET
SEATTLE Police say they arrested 17 people suspected of assault and property damage in Seattle Wednesday night when a May Day demonstration turned violent and marchers broke windows and pelted police with rocks, bottles and fireworks.
Police say eight officers suffered scrapes and bruises clashing in the streets.
The "anti-capitalism" protest followed a peaceful immigration reform march and rally earlier in the day. It was the second year in a row for May Day violence in the city.
Police had said 18 people were arrested but revised the number in a wrap-up on the police blotter.
Wednesday in an annual, nationwide ritual that carried a special sense of urgency with Congress considering sweeping legislation that would bring many of the estimated 11 million people living in the U.S. illegally out of the shadows.
In Seattle, protesters threw rocks and bottles at police officers and news crews. As they moved through downtown Seattle to another neighborhood, they flung construction street barriers, trash cans and newspaper bins on the streets in an attempt to stop police officers. Windows of businesses were broken and vehicles with people in them were banged around.
At one point, a crew from CBS Seattle affiliate KIRO-TV was surrounded by rowdy protesters. They spit and sprayed Silly String on KIRO reporter David Ham and hit his photographer, the station reports.
Police used their bikes to shield businesses and eventually began to use pepper spray and "flash bang' grenades -- releasing a flash of light, smoke and a loud noise -- to disperse the crowd. But that pushed the group to another nearby neighborhood, and they left overturned trash cans and debris on the street.
The department said one officer was injured after being hit by an object.
Initially, the protesters concentrated on a business sector of downtown Seattle.
This is the second year in a row violence has broken out during May Day in Seattle. Last year, anarchists broke windows of store fronts, including Niketown, and vehicles and used smoke bombs. Protesters also targeted a federal building, breaking windows and doors.
Olivia One Feather, of Covington, joined the crowd Wednesday night because she wanted to see how police handled the protest. She said she wasn't impressed, adding that she was pepper sprayed in the face while trying to video record officers.
"They don't have any manners. They don't say please or give you time to get out of the way," she said.
Of the protesters, she added, "(We're) doing what we need to do to stand up (for) ourselves. These are our streets and we have the right to take them."
Many of the protesters are self-described anarchists. A local anarchist website had said protesters would attempt to disrupt the day.
The violence marred a May Day that immigrant-rights activists hoped would put a focus back on immigration reform. Thousands of people marched about 2-1/2 miles from the Central District toward Seattle's downtown Jackson Federal Building after a May Day rally supporting immigrant rights and labor.
Many carried signs, with messages such as "We are America," and "There are no illegal humans." One sign suggested forgetting about marijuana and instead asking the United States to "Legalize my mom," a reference to Washington's recent legalization of marijuana.