RIO DE JANEIRO — A bomb squad is investigating after an apparent blast shook the area near the finish line of the men’s cycling road race.

Reporters could hear a loud boom on the press tribune and felt the ground shake as the cyclists had about 70 kilometers to go Saturday.

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 were cordoning off the area. No one was immediately evacuated, and it did not appear that anyone was injured. The race was continuing and had not been rerouted.

There is heavy security all over the city amid concerns about safety as the Olympics begin.