To subdue the crowd, police used water cannons and tear gas that even permeated the offices of the Seim building, the Polish parliament.
Earlier, the protesters broke through barricades near the parliament building and threw bottles, pieces of coal and hard hats at the police. Protesters were pushed toward the building of the Canadian Embassy and surrounded by the police.
The situation is reportedly under control now.
Several dozens protesters have been wounded, one of them severely after being hit by a powerful jet of water and landing awkwardly on the ground.
Ambulances were immediately called to the scene.
Six police officers have been wounded, one of them severely. He lost consciousness and was taken to a hospital.
