A suspected Islamic State militant stabbed a Turkish police officer to death while being taken to the Istanbul police headquarters, the state-run Anadolu news agency said.
The man, suspected of preparing a bomb attack, had been detained in an operation by anti-terrorism police. The wounded officer succumbed to his stab wounds after being taken to hospital, Anadolu said in a report late on Sunday.
Following the attack, police detained another 12 suspected Islamic State militants, of Iranian, Iraqi and Syrian origin, Andalou said.
Police detained 22 people suspected of links to the jihadist group on Friday.
Turkey has detained more than 5,000 Islamic State suspects and deported some 3,290 foreign militants from 95 different countries in recent years, according to officials. It has refused entry to at least 38,269 people.