Turkey says that Kurdish militants may be responsible for the two bombs that killed 38 people and wounded over 160.
The blasts - outside the stadium that is home to the Besiktas soccer team - came two hours after a football match ended.
There was no immediate claim of responsibility, but Deputy Prime Minister Numan Kurtulmus says early indications pointed to the outlawed Kurdistan Workers Party (PKK), which has carried out a three-decade armed insurgency, mainly in Turkey's largely Kurdish southeast.
The nation's Interior Minister Suleyman Soylu says 13 people have been detained in relation to the attack.
"Fourteen of the wounded are in intensive care. Five of them are undergoing surgery. 155 wounded are and are being treated in hospitals. We pray for their health. 10 people were initially detained regarding this incident. Three others have been detained later."
