The early morning blast almost completely destroyed the police headquarters in the southeastern town of Cizre, just north of the Syrian border and close to northwestern Iraq.
The explosion went off hours after the Turkish military shelled positions held by Kurdish militia inside Syria.
Ankara says the operation is aimed both at Islamic State (IS) jihadists and Kurdish fighters vehemently opposed by Turkey.
The bomb blast gutted the four-storey headquarters of the anti-riot police in Cizre, with television pictures showing a thick plume of black smoke rising into the sky.
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Cizre has borne the brunt of renewed violence between the outlawed PKK and government forces since the collapse of a ceasefire last year.
Eleven police officers were killed, the state-run Anadolu news agency reported, quoting the local governorate.
More than 70 people were injured, four of them critically, Health Minister Recep Akdag said in televised comments.
Anadolu said the bomb went off 50 metres (yards) away from the building at a control post, blaming the attack on the PKK.
Security forces closed the main road to Cizre from the provincial capital of Sirnak to the north after the attack, Anadolu added.
The latest bombing came at a critical moment with hundreds of Turkish forces and dozens of tanks deployed inside Syria in what Ankara has presented as a two-pronged offensive against Kurdish militia and IS.
Turkey on Friday sent four more tanks over the border into Syria, said an AFP photographer at Karkamis on the Turkish side of the border.
Kurdish activists have accused Turkey of being more intent on preventing Kurds creating a stronghold along its border than fighting IS jihadists.
Ankara's hostility to the YPG puts it at odds with its NATO ally, the United States, which works with the YPG on the ground in the fight against IS.
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