More than 300 firefighters and emergency responders battled a massive brush fire Sunday in Brooklyn that caused traffic jams and forced area residents to remain indoors. The fire at the Gateway Marina prompted police to close Flatbush Avenue in both directions from Marine Parkway to the Gil Hodges Bridge. As 65 units of firefighters attacked the blaze, an NYPD chopper dumped water on it. The fire, which was fueled by gusting winds, was extinguished by the early evening, but firefighters would be monitoring the site for hot spots overnight, officials said. One firefighter was taken to Coney Island Hospital for treatment of a minor injury.