The attack that took place yesterday evening in Mermer in Diyarbakir province, one of the areas in the mainly Kurdish southeast where security forces have engaged an offensive against the PKK since the collapse of a two-year ceasefire in July.
The attackers first detonated a van crammed with explosives outside the barracks and then opened fire on the police with automatic weapons, the sources said.
The military has responded with a barrage of airstrikes against PKK bases and by placing several Kurdish-majority towns under curfew during operations against PKK youth that have reduced whole districts to rubble.
In recent weeks the battle has spread beyond the southeast to western Turkey.
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