The road the bus was travelling has been built specifically for the games and cuts through an extremely dangerous part of Rio plagued by deadly crime and favelas.

American sports reporter Lee Michael, who is also an ex-airforce officer, told News Corp she heard the two shots and saw the windows blow out in the horror incident that occurred in the dead of night on Tuesday (Wednesday AEST).

“I’m familiar with the sound of gunfire. I dived to the floor and yelled for everyone to get down,” she said.

The bus then began to slow down before passengers yelled at the driver to speed up in an attempt to escape the carnage.

Michael said police then pulled the bus over but did not inspect the damage after briefly speaking with the driver.

Two passengers were bleeding with cuts as a result but were not seriously injured.

It was not known if the incident was a planned attack or stray bullets from nearby crime riddled neighbourhoods.

Amazingly, Rio police said the bus had been hit by rocks, despite eye witness accounts from those on board who saw bullet holes and heard the sound of gunfire.

The IOC said patrols would be increased in the area.