Now Playing: Lion proves he's king of the cuddle with tourists

Now Playing: Lion cub trio get clean bill of health

Now Playing: National Park Service researchers find litter of mountain lion kittens near LA

Now Playing: Countdown begins for Mega Millions $1.6 billion drawing

Now Playing: US bracing for possible nor'easter because of Hurricane Willa

Now Playing: Volunteers descend on Wisconsin town to search for missing teen

Now Playing: Plane crash-lands on busy California freeway

Now Playing: Utah student-athlete fatally shot while on phone with mom: Police

Now Playing: FBI investigating bomb found in liberal philanthropist's mailbox

Now Playing: Virus outbreak strikes NJ medical facility, killing 6 children

Now Playing: Shooting thwarted by report of Facebook message

Now Playing: Former Supreme Court justice reveals she's suffering from dementia

Now Playing: Vintage-plane crash shuts halts traffic on freeway in California

Now Playing: Pregnant wife performs CPR on husband suffering medical emergency, then gives birth

Now Playing: President Trump targets migrant caravan at Texas rally

Now Playing: Meghan McCain says she's thankful for her health on her birthday

Now Playing: Police hunt for 2 vehicles of interest in Wisconsin

Now Playing: Lottery jackpot drawing reaches historic high

Now Playing: University of Utah student athlete was on phone with mother when she was shot dead

Now Playing: Former Supreme Court Justice Sandra Day O'Connor announces dementia diagnosis