Public safety officials in Rio de Janeiro say a blast heard near the finish line of the men's Olympic cycling road race on August 6 was a controlled explosion of an unattended bag.
Members of a bomb squad team in protective clothing were operating at the site after the blast and a half dozen military police cordoned off the area.
The explosion shook the ground near the finish line as the cyclists had about 70 kilometers remaining in their race.
The race was allowed to continue and was not rerouted.
No one was immediately evacuated and there were no apparent injuries.
In recent days, bomb squads have detonated several unattended bags using controlled explosions in Rio.