Lambton OPP say three masked suspects robbed a bank on Arkona Road in Arkona on Tuesday evening.
Police said they entered the building at around 4:50 p.m. and locked the doors behind them.
The suspects brandished a firearm, and fled the building after stealing an unknown amount of Canadian currency from the vault.
They were last seen travelling southbound on Arkona Road, no injuries were reported.
Lambton OPP is asking anyone with surveillance footage, including video doorbell systems, or dashcam video from the surrounding area in the time leading up to and following the incident, to contact them at 1-888-310-1122.
Anonymous tips can be submitted to Crime Stoppers by calling 1-800-222-8477 (TIPS), or visiting www.sarnialambtoncrimestoppers.org.
A cash reward of up to $2,000 is available for a tip leading to an arrest.
