A remote-controlled roadside bomb ripped through a bus transporting Turkish military personnel and their families to a gendarmerie paramilitary base in Istanbul.
Turkish authorities say three gendarmerie sergeants and the 17-year-old daughter of a member of the security forces were killed in the attack, CNN informs.
The blast wounded nearly a dozen people and two were in serious condition, Istanbul's Provincial Governor Huseyin Avni Mutlu said. "This is a terrorist attack, and the aim of the attack is clear -- to create divisions, tensions and despair," he told reporters.
Kurdish separatists, based in northern Iraq, have increased attacks on military installations in Turkey's mainly Kurdish southeast, but they have also staged attacks in large cities in the past. Leftist groups and Islamist militants have also carried out bombings in Istanbul, Reuters says.