Reporters heard a loud boom on the press tribune and felt the ground shake.
An officer assigned to the event said it was a controlled explosion of an unattended bag. He did not give his name because he was not authorized to speak.
A half-dozen military police cordoned off the area. No one was immediately evacuated.
There is a heavy security presence throughout the city amid worries about safety as the Olympicsbegin.
There have been several bomb scares in the city the last couple weeks. A few blocks of the high-end neighborhood of Leblon were shut down two weeks ago when a doorman reported a suspicious package in front of a building. A bomb squad came out and found that the sports bag only contained clothes.
**Photo from Reuters via CBS News
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