Atilla Aydiner, the mayor for Istanbul's Bayrampasa district, also said five people were wounded in the explosion on Tuesday.
A pipe bomb exploded near the Bayrampasa Metro station in Istanbul during the evening rush hour. pic.twitter.com/JIWWlwhiHn— Sergio Quintana (@svqjournalist) December 1, 2015
Earlier, Istanbul's governor said one person was slightly injured in the blast and that it might have been caused by a faulty transformer.
The state-run Anadolu Agency said the explosion occurred at an overpass near the city's Bayrampasa station. Several ambulances were sent to the area.
Istanbul Gov. Vasip Sahin said at least one person was slightly injured.
NTV television said six people were injured. The Istanbul mayor's office said subway services in Istanbul were halted on the entire network following the explosion.