PORTLAND, Ore. (KOIN) — For the 6th time in 7 weeks, clashes between protesters and police escalated to a riot Monday night, this time outside the Portland Police Association headquarters on North Lombard.

It was the second time a riot happened at this spot as protesters blocked traffic and, police said, threw bottles, pieces of bricks, rocks, ball bearings and other items at law enforcement. Once a riot was declared in the early hours of Tuesday, several people were arrested.

A video began circulating on social media early Tuesday morning, showing an officer swatting a phone out of a protester’s hand, sending the phone flying into a window of the PPA building. In response, PPB stated that multiple warnings had been given and that “officers are permitted to take actions to protect themselves or others and to keep themselves safe.”

When and how will these protests end?

Dr. Randy Blazak with the Oregon Coalition Against Hate Crime told KOIN 6 News the recent addition of federal officers sent to Portland by President Trump to protect the federal courthouse in downtown only increases the response from demonstrators.

On Saturday night, one protester was seriously wounded after being shot in the head by an impact munition fired by a federal officer.

“The way we look for the end,” Blazak said, “is when there is dialogue between the two parties instead of us-versus-them locked in mortal combat. There starts to be open dialogue and brings the tension levels down.”