Violent Antifa protests are breaking out in Portland, Oregon, following the pre-planned “End of Domestic Terrorism” event taking place in the city.

City officials have been preparing for the potential of dueling clashes, with the police force at the ready and additional agencies on standby. According to journalist and editor of Quillette, Andy Ngo, – who warned that Saturday’s events had the potential to be a “powder keg” – things are already taking a violent turn.

One of Ngo’s videos shows protesters attacking a bus, appearing to attempt to pull people out of the vehicle:

Antifa attacks people on a bus. They try to pull them out and hit them with a hammer. #PortlandProtests pic.twitter.com/JSkCE1Vrcy — Andy Ngo (@MrAndyNgo) August 17, 2019

Another video shows a man who was allegedly maced and beaten by Antifa assailants.

“He was knocked unconscious to the ground. His partner or spouse was trying to protect him as mob still surrounded them. No police,” Ngo claimed.

Middle-age man was maced and beaten by an antifa mob. He was knocked unconscious to the ground. His partner or spouse was trying to protect him as mob still surrounded them. No police. #PortlandProtests pic.twitter.com/eAhrMSEKU1 — Andy Ngo (@MrAndyNgo) August 17, 2019

Man was beaten and maced by Antifa. He wandered off dazed and bloodied and collapsed in a parking lot. No authorities have helped him yet. #PortlandProtest pic.twitter.com/Jq36rhAF22 — The Post Millennial (@TPostMillennial) August 17, 2019

More:

A large antifa mob chase & attack a man & a young girl who got separated from the others. No police. #PortlandProtests pic.twitter.com/erceCRVnad — Andy Ngo (@MrAndyNgo) August 17, 2019

The police decided to stop protecting that small conservative group that got separated & antifa went after them. Man holding flag got a bunch of stuff thrown on his head. Not sure why @PortlandPolice left. Mob is following them. pic.twitter.com/bTlAUsUpbr — Andy Ngo (@MrAndyNgo) August 17, 2019

The aggressive antifa shirtless man who was threatening people was arrested by police. This angered the mob who said this was police bias. #PortlandProtests pic.twitter.com/OYDsyLw3EY — Andy Ngo (@MrAndyNgo) August 17, 2019

At least 13 people have been arrested during the demonstrations, police told CNN.