Four people were treated after they were exposed to a white powder at KeyBank in Coventry Saturday morning.
Police said an employee found an envelope containing white powder and a note in the overnight drop box.
It is unknown at this time what the substance is.
Police said the four employees exposed are not showing any signs of being sick but will be getting decontaminated.
The FBI responded to the scene to join the investigation.
Officials said there is no threat to the public and the investigation is ongoing.