Istanbul, Turkey (CNN) -- A remote-controlled roadside bomb ripped through a bus transporting Turkish military personnel and their families to a gendarmerie paramilitary base in Istanbul on Tuesday.
Turkish authorities say three gendarmerie sergeants and the 17-year-old daughter of a member of the security forces were killed in the attack.
A fourth wounded sergeant died in hospital hours after the bomb blast, an official at Istanbul's TEM Hospital told CNN, raising the death toll to five.
"It was a remote-controlled, fragmentation bomb that was left on the side of the road," said Huseyin Avni Mutlu, the governor of Istanbul, in a televised appearance broadcast live from the scene of the explosion. "This is a terrorist act".
The bomb attack took place in the western, European side of the city. Mutlu said the device hit the third and last of a three-bus convoy that was traveling to the Istanbul Province Gendarmerie Command Center.
