Clashes between Egyptian riot police and protestors in Cairo left 388 people injured on Thursday night, one day after a riot killed 74 people in a stadium in Port Said, state TV reported.Security forces fired tear gas at protestors to prevent them from reaching the Interior Ministry building near Tahrir Square. The protestors chanted slogans against police and held them accountable for allowing fans to enter the stadium with sticks and knives. Clashes also erupted between protestors and police in Suez governorate on Thursday, state TV said. Post-match riots between fans of the football teams of el-Masry and el-Ahly in Port Said on Wednesday night left 74 dead and hundreds injured. The Interior Ministry said 47 people have been arrested.The ruling Supreme Council of the Armed Forces announced a three-day national mourning over the tragedy from Thursday to Saturday. Hussein Tantawi, head of the military council, has ordered the formation of a fact-finding committee to probe the clashes in the Port Said Stadium. He said police should be responsible for the security of games.Egyptian Prime Minister Kamal el-Ganzouri on Thursday sacked Port Said Governor Mohamed Abdel Hashem. The provincial security chief, Essam Samak, and the board of the Egyptian Football Association were also fired. At an emergency session of the People’s Assembly over the deadly football riot, Ganzouri extended deep condolences to the Egyptian people over the incident and said he shouldered the political responsibility for the violence. On Friday, a big rally is called for in Cairo. The country faces fresh protests due to the latest violent event.