The Fort Frances financial institution was closed last Thursday after a bag and a note asking staff to fill it with money was found at its back door.
OPP Constable Anne McCoy says it also made threats to other locations if the demand was not met.
As a result, all schools in Fort Frances were placed in a "hold and secure" position, requiring them to lock all doors and closely monitor those entering.
OPP confirm they're reviewing video tape from security cameras as part of their investigation.
Anyone with information can call the OPP or Crimestoppers.
