Four people have been released from police custody, after a gun was discharged outside a Hamilton hotel.

Hamilton police say no one was injured when a gun went off outside the Staybridge Suites Hotel Monday night.

More than a dozen officers, including a tactical team and a tracking dog, surrounded the parking lot at the intersection of Caroline and George Streets.

Police evacuated one floor and locked down another floor.

A shell casing was found outside, indicating a shot was fired.

No charges have been laid.