Police in Brussels surrounded a group of demonstrators about 500-strong who descended Sunday on a memorial for those killed in terror attacks earlier in the week.
Some of the marchers were thought to be a part of the right-wing group "The Nation." They carried anti-ISIS and anti-terror signs and chanted as they made their way to the Brussels Stock Exchange, where they were met with police in riot gear.
The police fired a water canon at the group at least once — as crowds who were originally there to hold a peace rally in the square cheered.
As the protesters were pushed back by officers, they shouted: "This is our home." Most were clad in black, while some were masked.
Cheers later rang out as members of the peaceful group were able to string a banner of more than a dozen nations' flags tied together across the length of the steps outside the stock exchange building.
Shortly after the flags were hoisted, at about 4 p.m. local time (10 a.m. ET), relative calm was reestablished in the square.
This story first appeared on NBCNews.com.