There were some tense moments for employees at the Canada Post Distribution centre at Avenue H and 22nd Street late Wednesday morning.The building was put on lockdown after a “suspicious substance” was found. Crews later determined the substance was an “artificial sweetener.”A fire engine, haz-mat unit, decontamination unit, mobile command and emergency crews were called to the scene at 11:22 a.m. Wednesday.Employees that were in contact were put into isolation and the building was evacuated.Nearby schools were not affected by the incident.Emergency crews left the scene at 12:45 p.m.There were no injuries, and there is no risk to public safety.