Police say a female prisoner used a lens from a pair of eyeglasses to take a fellow prisoner hostage at the Edmonton courthouse.
The tactical unit and negotiators were called to the downtown building shortly before noon.
Insp. Dean Hilton says officers found one woman holding another woman hostage in the cells area.
Both women were waiting to appear in court at the time.
Hilton says a negotiator managed to talk the woman into giving herself up and she was taken to hospital for observation.
The situation was over in less than two hours.