Three police officers and one civilian were killed and 15 police wounded Wednesday when two unknown attackers fired at a police service bus in the south-eastern Turkish city of Diyarbakir, the NTV private television station reported.
The service bus was carrying police officers from a police school in the city when it was attacked at around 5 pm (1400 GMT). The attackers fled the scene and police launched a large-scale search operation, reported dpa.
Turkish media said that the attack was similiar to others carried out by the Kurdish Workers' Party (PKK) and may have been carried out in protest against a debate Wednesday in the Turkish parliament on whether to extend for a year a mandate allowing the Turkish military to launch cross-border operations.
The PKK uses the mountainous terrain in northern Iraq as a base from which to launch attacks inside Turkey.
The extension of the mandate was expected to pass easily later on Wednesday.