A 13-year-old boy has been shot dead during clashes in Port Said after the Egyptian city's football team was suspended, state media reports.
Dozens of people were also injured as hundreds of angry fans of the al-Masry club battled security forces.
Al-Masry, one of Egypt's top teams, have been banned for two years over violence at its stadium in February in which at least 74 people died.
A criminal investigation into that incident is continuing.
The suspension of Al-Masry means the team will not compete in competition until the end of 2013.
Hundreds of angry Al-Masry fans took to the streets of Port Said on Friday evening to protest against the ruling, besieging a government building. Troops fired into the air to try to disperse the crowds.
The official Al-Ahram newspaper said a 13-year-old boy died in hospital after being shot in the back and that dozens of people were injured as the army tried to prevent protesters from reaching the Suez Canal.
Reuters news agency quoted a medical source as saying that two more people were being treated for gunshot wounds.
February's violence erupted at al-Masry's stadium following a game against Cairo team, al-Ahly.
Al-Ahly have been ordered to play four games behind closed doors. The club's coach and captain have been suspended and fined.
Supporters of the Cairo club have denounced the punishment on al-Masry as weak, saying they would hold a sit-in at the team's grounds on Sunday.Authorities blamed
The two teams are long-standing rivals whose games have required a large security presence.
Al-Masry won February's home game 3-1, but as the game ended their fans invaded the pitch, attacking al-Ahly players and fans.
Rumours that the police had failed to intervene sparked days of clashes across the country in which a further 16 people died.
There were also claims that fans had been allowed to take knives and other weapons into the stadium.
In the days after the riot, large protests blaming the military government for the deaths were held outside the interior ministry in the capital, Cairo.
Last week, Egypt's chief prosecutor charged 75 people with murder or negligence over the 1 February violence.
Nine police officers were reportedly among those facing charges.
The BBC's Jon Leyne in Cairo says Egyptian football fans are notoriously violent, particularly a section of al-Ahly supporters known as the Ultras.
They were heavily involved in confronting the police during last year's political protests, and many Egyptians believe the authorities either orchestrated the violence or allowed it to continue to punish al-Ahly for their involvement.
The football league season was cancelled in the wake of the unrest and has not yet restarted.