Police used tear gas to disperse crowds inside and outside the stadium at the Catania-Palermo derby.
Play was suspended after an hour when the gas drifted onto the pitch, affecting players.
About 100 people were injured in the clashes, while nine were arrested.
A policeman, Filippo Reciti, was killed when an explosive device was thrown inside his vehicle. Another policeman was critically injured.
News of Officer Reciti's death provoked grief and anger, with the Italian Football Federation (FIGC) deciding to suspend all matches indefinitely.