ISTANBUL, TURKEY - MARCH 3 : A helicopter belonging to the Turkish security forces is seen over an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Onur Çoban - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Onur Çoban - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Onur Çoban - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Onur Çoban - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Onur Çoban - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Onur Çoban - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : Turkish security forces cordon off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : People are seen outside a school to take their child who are in a school next to the cordoned off area in Istanbul, Turkey on March 3, 2016. Turkish security forces cordoned off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : People are seen outside a school to take their child who are in a school next to the cordoned off area in Istanbul, Turkey on March 3, 2016. Turkish security forces cordoned off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )
ISTANBUL, TURKEY - MARCH 3 : People are seen outside a school to take their child who are in a school next to the cordoned off area in Istanbul, Turkey on March 3, 2016. Turkish security forces cordoned off an area where alleged suspects who have hurled hand grenades and open fired at police special forces headquarters were thought to be trapped in a neighbouring building in Istanbul, Turkey on March 3, 2016. ( Salih Zeki Fazlıoğlu - Anadolu Ajansı )