Olympics-Athletics-U.S. win sixth straight gold in women's 4x400 relay

By Scott Malone RIO DE JANEIRO, Aug 20 (Reuters) - The United States won the Olympic women's 4x400 metres relay gold medal on Saturday in 3 minutes 19.06 seconds, their sixth straight victory in the event at the Games. Jamaica took silver and Britain the bronze. American Courtney Okolo grabbed the lead in the opening stage and her team never relinquished it, opening a big gap on the rest of the field with Jamaica by the halfway point. The U.S. gold streak in the event started at the 1996 Atlanta Games. American Allyson Felix claimed her third medal of the Rio Olympics having won gold in the 4x100m relay and silver in the individual 400m. (Reporting by Scott Malone, editing by Ed Osmond)