At least three police officers were killed, and eight other people including civilians were injured when suspected suicide bombers blew themselves up in the southeastern Turkish city of Gaziantep on Sunday.
The incident took place during a police raid on what was thought to be a Daesh safehouse, security sources and medics said.
Gaziantep Governor Ali Yerlikaya told Anadolu Agency that four Syrians were also among the injured.
Yerlikaya said security forces would continue their anti-terror operation for the peace and safety of the people of Gaziantep.
Police pursued a vehicle believed to be carrying explosives to the house, where a group of Syrian nationals were thought to be sheltering, and raided it, the security sources said.
Gaziantep lies around 40 kilometres (25 miles) from the Syrian border.
In August, Turkey launched a military operation into Syria, in support of Syrian opposition forces, to oust Daesh from its border.
The Turkey-backed Free Syrian Army said on Sunday it captured the Daesh-held village of Dabiq in Syria, a stronghold where it had promised to fight a final, apocalyptic battle with non-Muslims.
A suicide bomber suspected of links to Daesh killed more than 50 people, many of them children, at a Kurdish wedding in Gaziantep in August.