(CNN)Demonstrators were ordered Saturday afternoon to leave the downtown Portland area where left-wing anti-fascist protesters gathered to counterprotest a rally by far-right and extremist groups.

Portland police declared the protests a civil disturbance, and they told people to leave immediately.
“This means everyone,” they tweeted. The order came after crowds blocked streets.
At least 13 people were arrested Saturday during seven hours of demonstrations, police said.
It was unclear which groups the arrested persons were affiliated with.Police tweeted that one person who was injured during the day’s events was taken to a hospital. Four other people who also had minor injuries were evaluated on scene, Portland police Lt. Tina Jones said.
Saturday’s demonstrations came after days of Portland authorities condemning hate and warning residents to stay home as far-right groups planned a rally aimed at putting an “end to domestic terrorism,” with a particular focus on Antifa extremist groups.
There were fears the rally could prompt violent clashes between both a smattering of right-wing extremists and Antifa counterdemonstrators, like those the city has seen in recent years. By late morning, Portland police had said they already seized items like bear spray, shields and metal and wooden poles from “multiple groups.”
Law enforcement worked to keep the opposing groups separate, Jones said. By early afternoon, she said, there had been “limited interactions between individuals.”
Saturday morning, before events in Portland had gotten underway, President Donald Trump said “major consideration” was being given to designating Antifa an “organization of domestic terror.” He added, “Portland is being watched very closely. Hopefully the Mayor will be able to properly do his job.”

Major consideration is being given to naming ANTIFA an “ORGANIZATION OF TERROR.” Portland is being watched very closely. Hopefully the Mayor will be able to properly do his job!

— Donald J. Trump (@realDonaldTrump) August 17, 2019

Mayor Ted Wheeler responded to the President’s tweet in an interview with CNN Saturday, saying, “My job today is to be heads down and focused on maintaining the public safety here in Portland, Oregon. I’m focused on what’s going on the ground here in my community.”
“And frankly, it’s not helpful,” Wheeler added. “This is a potentially dangerous and volatile situation, and adding to that noise doesn’t do anything to support or help the efforts that are going on here in Portland.”
CNN’s Sara Sidner, Mallory Simon and Hollie Silverman contributed to this report.