A blast shook the Olympic stadium in Rio after police found a suspicious device on Monday.
Brazilian police reportedly found a toolbox in the Maracanã Stadium and sent in a robot to deal with it.
There was apparently a loud explosion when the robot touched it, and Brazilian authorities are calling it a “controlled explosion”.
No one is reported to be injured.
The famous Maracanã Stadium will host the opening ceremony of the 2016 Olympics on Friday, and the closing ceremony after the Games.