Sources told the A.A correspondent the blast occurred while the bus was passing in front of the Turkish aid organization Kizilay (Red Crescent) Blood Center, killing three and injuring eight.
Istanbul Governor Muammer Guler and Security Director Celalettin Cerrah are at the scene of the explosion.
Meanwhile, it was claimed that the explosion happened after an 18-year-old girl got off the bus. (UK-AÖ) (YE)
