ATHENS (AFP) - Two police officers were arrested on Sunday over the killing of a 15-year-old Athens boy, including the officer suspected having fired the fatal shot, police said. Epaminondas Korkoneas, 37, who allegedly shot and killed Andreas Grigoropoulos late on Saturday was taken into custody, as well as Vassilis Saraliotis, 31, who was in the police car when the incident happened, the source said. The shooting has provoked an outpouring of anger across Greece with hundreds of protesters clashing violently with police in a night-long display of anger. At least four policemen were injured in the demonstrations which flared up in several cities across the country, from Athens and Salonika in the north, to the southern island of Crete. The clashes continued through Sunday morning in both Athens and in Salonika, Greece's second largest city. In central Athens, a group of masked youths threw stones and molotov cocktails at police officers who responded with tear-gas in front of a university. Other groups held siege at the polytechnic school in the Exarchia district, where Grigoropoulos was shot by a police officer who opened fire after youths threw objects at his car. In Salonika, a dozen banks and shops were torched by protesters as around 2,000 demonstrators rallied in the city centre. The windows of Salonika's city hall were broken, and the Greek National Bank and Emporiki Bank were targeted as well as clothing stores and supermarkets. Demonstrators initially took to the streets of Athens late on Saturday to protest the "arbitrary" police action, shouting slogans against the right-wing government of Prime Minister Costas Karamanlis. Youths set fire to garbage bins in the central Exarchia district, scene of frequent clashes with police. The anger spread to other cities as protesters set about 20 cars on fire in Athens, Salonika and western Patras through the evening. The facades of 17 banks in Athens and five in Salonika were damaged, while some businesses were also attacked. Demonstrators threw molotov cocktails at the police station in Patras. On the island of Crete, three banks in the main city of Iraklion were damaged while molotov cocktails were tossed at city hall in the town of Chania. Grigoropoulos was among a group of about 30 youths who threw stones and other projectiles at a car transporting two police officer. One of the officers got out of the car and opened fire, hitting the teenager with three bullets. He was taken to a nearby hospital where he was pronounced dead of a chest wound. Interior Minister Prokopis Pavlopoulos called for an "exemplary punishment" against those responsible for what he termed an "isolated incident." Three prosecutors were tasked with investigating the shooting, while the Athens Press Agency reported that the chief of the police station in Exarchia and the two police officers involved in the shooting were suspended. Pavlopoulos and the police expressed "deep regret" over the shooting. "Police keep watch and try to ensure order for citizens by defending themselves ... but this type of isolated incident that led to the death of a youth is never justifiable," Pavlopoulos said. He called on human rights groups and leftist organisations planning protests on Sunday to avoid "extreme acts." Pavlopoulos and junior minister Panayotis Hinofotis offered their resignations to the prime minister, who did not accept them. In 1985, 15-year-old Michalis Kaltezas was shot by a police officer, triggering violent clashes between far-left youths and the police in Exarchia.