Investigators said three cylinders found on a Metro bus on Monday evening were explosive devices.
The Hamilton County Hazardous Devices Unit determined that the 4 1/2-inch-long cardboard tubes contained high-grade flash powder and had an internal fuse with an external heat source.
Officials said that if the three had gone off in unison under a passenger's seat, the victim could have suffered severe injuries or even been killed.
"We're not really sure that this was an intentional act," said Metro spokeswoman Sallie Hilvers. "This could've been something that fell out of someone's backpack or pocket while they were sitting in that back seat of the bus, because it wasn't near a heat source, so it wasn't going to go off on its own from what we understand."
The driver found the explosives just after 6 p.m. as she pulled into a layover area along Wexford Avenue .
She called firefighters, and a nearby church was evacuated while the bomb squad removed the explosives.
No one was injured during the incident.
Anyone with information on the person who left the devices on the bus should call Crimestoppers at (513) 352-3040. Callers can remain anonymous and could receive a reward.
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