An operation was launched to hunt down the assailants, the sources added.
The PKK has stepped up violence in the southeast over the past several months, after it called off a five-year unilateral ceasefire in June 2004 on grounds that reforms by Ankara to expand Kurdish freedoms were inadequate.
The group, blacklisted as a terrorist organization by the United States and the European Union, was also blamed for a July 16 bomb attack in a popular seaside resort in the west which killed five people including foreign tourists.
The bloody conflict between the PKK and Turkish army between 1984 and 1999 left some 37,000 people dead.