RIO DE JANEIRO, Brazil (AP) _ A gas leak triggered an explosion on an offshore oil drilling platform Monday, injuring nine workers, three critically, the state-run oil company said.

The blast in the Campos Basin off the Rio coast occurred on Brazil's largest oil platform, which produces 57,000 barrels per day, said a spokesman for the Petrobras Oil Co.

A fire caused by the explosion was under control Monday night and the platform was producing again, Petrobras said.