An officer was stabbed to death near a police station in Istanbul on Sunday by a suspected member of ISIS, Turkish media said.
The attacker, who was suspected of preparing to carry out a suicide bombing, was shot dead after killing the policeman, the pro-government Anadolu news agency reported.
The private Dogan news service said the assailant had already been arrested and was being transported to a police station when the stabbing occurred at around 11 pm (2000 GMT).
The officer died from his wounds after leaving the scene in an ambulance, Dogan said.
It was not immediately clear how the man managed to keep a knife while being taken into custody.
Turkey was hit in 2016 by a succession of attacks that left hundreds dead in the bloodiest year of terror strikes in its history.
The attacks were blamed on ISIS extremists who had taken swathes of territory in neighboring Syria and Iraq as well as the outlawed Kurdistan Workers Party (PKK) who have battled the Turkish state in an insurgency lasting more than three decades.
An attack by an extremist gunman on an elite nightclub in Istanbul just 75 minutes into New Year's Day in 2017 left 39 people dead, mainly foreigners.
There has since been a lull in similar attacks, but tensions and high security remain in big cities.