Authorities say a man who entered the Blue Water YMCA building Monday morning was an unarmed construction worker and did not pose a threat to public safety. The Port Huron Police responded to a call Monday morning on reports of a suspicious looking man seen entering the building. Police tell WPHM that a witness believed the man was potentially armed. Authorities searched the building and reviewed surveillance footage form the site. Shortly after 10am, police were able to confirm to WPHM that the suspicious man was indeed a construction worker and he was not armed. As a precaution, authorities locked down the YMCA Monday morning and advised SEMCO workers to shelter in place.