Now Playing: Illinois zoo introduces baby wallabies
Now Playing: Animals cool down at Moscow Zoo
Now Playing: Lemur twins born at Colorado zoo
Now Playing: 2 men rescued from top of truck amid flash flood
Now Playing: Boat accident kills 1
Now Playing: Washington state deputy fatally shot in line of duty
Now Playing: Extreme weather threats across US
Now Playing: COVID-19 cases among adolescents grow rapidly in US
Now Playing: Body camera video shows police use stun gun on 75-year-old man
Now Playing: US Olympians go for gold as controversy continues to surround Games
Now Playing: After more than 106 years, Cleveland’s baseball team is getting a new identity
Now Playing: Women could be drafted in must-pass defense bill
Now Playing: Husband named person of interest in disappearance of Maya Millete
Now Playing: NFL announcing hardline policies for unvaccinated players
Now Playing: More than 8 fires across 13 states fueled by dangerous weather conditions
Now Playing: New model predicts surge in COVID-19 cases could continue until mid-October peak
Now Playing: Delta variant is now dominant strain in US
Now Playing: Officials push to vaccinate as hospitals see rise in COVID-19 patients
Now Playing: ABC News Live Prime: Friday, July 23, 2021
