The deaths were the first since Sunday's election that returned the Justice and Development Party (AKP) to power and occurred a day after Turkish warplanes bombed rebel bases in both Turkey and Iraq.
A 22-year-old suspected member of the Kurdistan Workers' Party (PKK) was killed in the Silvan district of Diyarbakir province, the local governor's office said, after a curfew had been imposed in the area.
Another two members of the PKK youth branch were killed in the Yuksekova district of Hakkari province when police tried to tear down barricades built by the rebels, security sources told AFP.