Authorities are investigating how a suspicious powder ended up inside a night deposit box at a Los Fresnos Wells Fargo.
The building was evacuated around 12 p.m. Thursday, after employees noticed a white powdery substance dumped inside the bank's night deposit box.
City Manager Mark Milum told Action 4 News employees quickly called 911.
Los Fresnos Police and Fire Departments along with Brownsville's Hazardous Material Unit were called to the scene to assist.
After nearly two hours, HAZMAT teams learned the white powdery substance was sodium bisulfate.
It is reportedly used to treat cyanide poisoning and ring worm.
Milum told Action 4 News it is not dangerous if humans come in contact with it.
Authorities did tell Action 4 News employees would be allowed back into the building around 3 p.m. Thursday.
For now, an investigation is underway to determine how the substance got into the night drop box, and why someone would leave it there.