welcome back to "the lead." our world lead, dramatic video coming in from turkey, officials say this explosion that rocked an intersection near a subway station in istanbul was a bomb. the blast came 6:00 p.m. turkey time, height of rush hour. cnn's ian lee joins me from istanbul. what are you learning about the investigation at this hour? >> reporter: well, jake, the bomb blast was heard across istanbul, we are learning that they believe it was a bomb that exploded. earlier they thought it could have been a transformer. if you look at this video, we're also hearing that they believe they know the target of this bomb. before the blast goes off, you can see a vehicle moving by. they're saying that that was a bus carrying riot police, they believe that is the target. one person was injured, they suffered minor injuries.