Fifteen people have been injured after a bomb blast hit a police bus in Istanbul, the Anatolia state news agency reports.
It said the bomb exploded in the Kucukcekmece district on the outer edge of the western side of the city, as the bus was passing.
The injured included at least two police officers as well as a number of civilians, Anatolia said.
No immediate claim of responsibility was reported.
"It looks like a bomb that was placed by the side of the road," Istanbul police chief Huseyin Capkin was quoted as saying.
"It may have been set off by remote control."
Most of the injuries were from shrapnel and none of them were serious, Turkey's NTV reported.
In the past, Istanbul has suffered bomb attacks by Islamist militants, Kurdish rebels, and left-wing extremists.
Tuesday's bombing came as Turkey was hosting an Asian security meeting attended by leaders including Iranian President Mahmoud Ahmadinejad, Afghan President Hamid Karzai, and Russian Prime Minister Vladimir Putin.