SEATTLE -- Seattle police rushed to the scene of a violent protest on Thursday afternoon after officers heard a colleague radio for backup.

A crowd of protesters then raced in, tangling with police.

Police were trying to arrest someone in a dispute over a flag when protesters began wrestling with police.

Slideshow: Police, Protestors Clash On Capitol Hill

Officers had to fight off protesters who were grabbing onto those already arrested, KIRO 7 Eyewitness News reported.

The protesters said they were provoked by police and were fighting for their flag, which police took.

“We were trying to protect the flag that was for our protest, and I got my hands shoved into a tree by one of the cops,” one protester said.

Police said they were trying to keep order when they were shoved and punched by surrounding protestors.

“People in this country have been looking for a vehicle to give expression to that outrage and ‘The World Can't Wait’ drives at the Bush regime as that vehicle," Maggie Lawless with The World Can’t Wait said.

Seattle was one of more than 190 communities that took part in protests Thursday across the U.S. and Canada.