Donetsk, Ukraine (CNN) -- Pro-Russian activists and Ukrainian riot police clashed Thursday inside the compound of the prosecutor's office in the eastern city of Donetsk, as simmering tensions escalated into violence. As a result of the clashes, 26 people sought medical help, four of them for gunshot wounds, the Donetsk regional administration's health department said. Two remain hospitalized. At least one police officer was injured in the clashes, the Ukrainian Interior Ministry said, adding that shots were fired and small grenades and stones were used in the attack. Police fired tear gas and stun grenades in an effort to disperse the activists, who were armed with clubs, batons and shields but did not appear to be carrying firearms.
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NEW: Donetsk health authority says 26 people sought medical help, 4 with gunshot wounds
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The yellow and blue @placeholder flag, which had been flying until a short time before, was thrown off the side of the building, a symbol of the spreading unrest.