Portland's mayor and police chief said peaceful protests have been hijacked by people who, "simply want to fight with police."

Chief Mike Marshman and Mayor Charlie Hales spoke Saturday about the continuing protests. On the fourth straight night of protests Friday, 17 people were arrested and police in riot gear deployed flash bangs and tear gas.

"We're done with criminal activity in this city," Marshman said. "It's time to move on and move forward."

Marshman said once the crowd of thousands began blocking streets, they were told it was an unlawful gathering and they needed to leave.

He said that's when people in the crowd turned violent.

"My officers took rocks, they took bottles, they had fireworks shot at them," Marshman said.

Hales said anyone upset about the election results should now start looking for ways to make a difference. He suggested volunteering with organizations like the ACLU, Planned Parenthood, Basic Rights Oregon and the Sierra Club.

"If you are upset about the election of Donald Trump and you want change, there are ways to do that," Hales said. "They don't involve taking to the streets with signs anymore."

Marshman said they will continue to work toward arresting destructive and violent protesters from the last several nights.

"Our intent is to go arrest everybody who has committed a crime," he said.

Copyright 2016 KPTV-KPDX Broadcasting Corporation. All rights reserved.