It happened at 2:45 p.m. Monday.
Fire department officials told Action News a man arrived at the emergency room complaining that he felt sick.
He showed emergency room personnel an open envelope containing some kind of white powder.
The fire department and a HAZMAT team were called, and the man was taken to a decontamination shower.
Part of the emergency room was closed as crews investigated, and ambulances were diverted to another entrace of the hospital.
The powder was found to be harmless.
The emergency room was back open and functioning at full capacity by 4:00 p.m.