Three people have been killed and at least six injured in a gunfight during a raid by police against an armed group in Istanbul.
Authorities said those killed included an alleged leader of the Revolutionary Headquarters, which is said to have links to the Kurdistan Workers' Party (PKK), a Kurdish separatist group.
Besir Atalay, Turkey's interior minister, said a civilian and a police officer were also killed.
Muammer Guler, Istanbul's governor, said the police raid was one of at least 60 carried out in the city overnight, against groups planning "sensationalist attacks".
The shooting broke out soon after police began their raid on an apartment block in the Bostanci area of the city at 5:30am (02:30 GMT) on Monday.
"These are extreme leftist, separatist and radical groups. There are more than 10 [people] detained in the operations," Guler told the Turkish broadcaster NTV.
"Terrorists responded by throwing bombs in some places and seven policemen were wounded," Guler said.
Witnesses said automatic gunfire and sporadic blasts were heard as the raid went ahead, and that tear gas was used by the police.
Police said members of the armed group killed one civilian and injured a television cameraman during the shooting.
Guler said the wider police operation was aimed at foiling attacks by left-wing extremists and the PKK.
The governor said that about 40 people had been arrested during the raids by midday on Monday.
In recent years, Turkey has focused its efforts on cracking down on members of the PKK which is fighting for greater autonomy for the Kurdish community.
But several armed left-wing and radical religious groups are also active across the country.
The police raids came days before May Day, when the authorities are usually put on alert for possible clashes with opposition groups.