The incident happened Sunday as the bus driver, Christopher Battle, 53, was driving near a busy intersection, The (Cleveland) Plains Dealer reported.
The driver lost control of the bus, which then crossed over a sidewalk and down another street, said Sgt. Mark McArter. Two vehicles struck the bus before it crashed into a signal control box. McArter said police are awaiting an autopsy to determine Battle's cause of death. "We're not sure. It might have been a medical issue," he said.
Three others were injured in the incident and were transported to local hospitals, McArter said. None of them had life-threatening conditions.
Police are investigating the incident.