ISTANBUL - One police officer has died in Istanbul’s Sultangazi district, after a suicide bomber threw a grenade into a police station in the area, Turkish news channel NTV reported.

Up to five people were injured and taken to hospital in critical condition, according to Daily Hurriyet.

"First (the attacker) threw a grenade, then blew himself up at the entrance of the police station, where the X-ray machines are located," Istanbul police chief Huseyin Capkin told reporters.

Capkin said the attacker was 25, but declined to comment on his identity. No organization has claimed responsibility for the attack, but previous domestic attacks have been linked to the outlawed Kurdistan Workers Party (PKK), who is classed as a terrorist organization by Turkey, The United States and the European Union.

The unrest in Syria has lead to an increase of attacks by the PKK in the Southeast region of Turkey.  The PKK took responsibility for a similar suicide attack in the central province of Kayseri in May.

Tuesday’s attack comes a day after dozens of Kurdish journalists were tried on various terrorism charges, including accusations of support for the PKK. Some 36 of the suspects have been detained since December.