Fans of historic Argentine soccer team River Plate fought running battles with police after the team was relegated to the second division for the first time in its 110-year existence.
Violence broke out a minute before the match with the Belgrano side was over. Angry fans pelted players with objects from the stands, and police replied with high-powered fire hoses with some fans climbing fences topped with razor wire.
As fans were pounded with jets of water, River Plate's players huddled on the pitch, many in tears, including goalkeeper Juan Pablo Carrizo.
The mayhem quickly spread outside River's 50,000-seat stadium. Alberto Crescenti, head of emergency medical services, said at least 55 people had been injured.
Nilda Garre, the minister for security, said 35 police officers were injured.
"Fortunately, none have their lives at risk," she said.
Police used water cannons outside the stadium immediately after the match, hoping to disperse fans quickly. Fans who poured out of the stadium faced police with batons and shields at every exit, while attack dogs were ready and helicopters hovered over the stadium.
The area outside the stadium, located in the leafy northern suburb of Nunez, looked like a war zone with police battling hand to hand with River Plate hooligans, who are known by the colourful nickname "Los Borrachos del Tablon" - the Drunks in the Stands.
Police fired rubber bullets and tear gas, and brought in mounted units to try to keep order.
Young, angry fans responded by throwing rocks at police, setting fire to rubbish bins and vehicles, and ripping down metal street barriers. Smoke also billowed from one end of the stadium with reports that concession areas and other parts of the stadium had been set on fire.