A car bomb attack has killed four Turkish police officers and wounded 20 other people in the southeast city of Diyarbakir, the latest violence to hit the biggest city in the largely Kurdish region.
The attack on Thursday (local time) targeted a minibus carrying members of the police special forces, a security source said, adding that civilians were also among the wounded.
The explosion hit the vehicle as it passed near a bus station in Diyarbakir, broadcaster Haberturk TV said.
The southeast has been scorched by waves of violence since a ceasefire between the outlawed Kurdistan Workers Party (PKK) and the government collapsed last July.
There was no immediate claim of responsibility for the attack.
A PKK offshoot has claimed two car bomb attacks this year in the capital Ankara.
The first, on February 17, targeted a military bus and killed 29 people, most of them soldiers.
The second, just under a month later, tore through a crowded transport hub and killed 37 people.
NATO member Turkey faces multiple security threats.
As part of a US-led coalition, it is fighting Islamic State in neighbouring Syria and Iraq.
In the southeast, the collapse of the two-and-a-half-year ceasefire has meanwhile triggered some of the worst violence since the 1990s.
In Istanbul this month a suicide bomber, who the government said was a member of Islamic State, killed three Israeli tourists and an Iranian.