Tensions between members of a right-wing group advocating for greater law and order and antifa counterprotesters boiled over Saturday in Portland, Ore., in violent clash that reportedly included the use of bear spray and clubs.

Riot police were able to put a stop to one of the brawls with pepper balls after fighting broke out at the Patriot Prayer rally as participants marched through the city's downtown district, according to the Oregonian.

No immediate arrests were made but Portland Police were still investigating with the help of witnesses, as well as video and photos of the event, the Associated Press reported. Four people received medical assistance, but local authorities were unaware if anyone was taken to hospital for further treatment.

The “Flash March for Law and Order” demonstration was reportedly organized by Patriot Prayer leader Joey Gibson following a protest last week against police brutality triggered by the shooting of Patrick Kimmons, a 27-year-old black man, according to Fox News. The violence on Saturday erupted near a makeshift memorial erected in Kimmons' honor.

Law enforcement officials were criticized for their management of the previous rally after Kent Houser, 74, was confronted by activists as he drove near where they were gathered. Houser, however, has also been scrutinized for driving his car so close to the group when a vehicle was weaponized against counterprotesters at the 2017 United the Right rally in Charlottesville, Va.