what testress vealed about the oil that is still coating and killing some local wildlife >>> officialsre starting to learn more about that oil slick on the potomac just north of reagan national airport. the first test results came back today, and the substance apparently contains fuel oil it's still not clear where it came from. since it was first reported a week ago, state and local agencies have been working to contain it, clean it up, and rescue wildlife in the area. so far more than 30 oil covered canada geese have been rescued and taken to a facility in delaware for decontamination. one of them has died. >>> mark your calendars. six months from today, nbc takes you down to rio de janeiro. that's when 10,000 athletes and two million spectators from all over the world head to its sunny coastline to celebrate the olympic games. our own wendy reiger went down to rio to soak in all the city is doing now to get ready. >> reporter: start swaying your hips because rio is not about standing still. and since it was anointed with the 2016 summer games seven years ago, it has been in motion,