DIYARBAKIR - A prominent Kurdish lawyer and rights activist was shot in the head and killed in a street shootout on Saturday, an incident likely to fuel further unrest in Turkey's mostly Kurdish southeast.The pro-Kurdish HDP Party called the killing of Tahir Elci a "planned assassination" and urged people to protest. Prime Minister Ahmet Davutoglu said it was unclear whether Elci was caught in crossfire or assassinated.Hours later, police fired tear gas and water cannon to disperse hundreds of people marching in Istanbul to protest against the killing. The marchers chanted: "Shoulder to shoulder against fascism," and "Tahir Elci is immortal."Reuters TV footage showed plain clothes police repeatedly shooting at a figure running past them towards Elci. He was then seen lying on the ground with blood apparently streaming from his head.