Transcript for San Francisco Is Under Siege Making a Bat Call Cry for Help as Bat Kid Saves the Day
story we simply love. A conspiracy of kindness by an american city pulling together to make a five-year-old boy's wish come true. So many kind hearted and creative strangers were saved today by the newest and tiniest super hero bat kid. Here's the story. Reporter: San francisco under siege this morning. We begin this morning's broadcast with breaking news from san fran's hall of justice. Please caped crusader, we need you. And bring the bat kid. Reporter: The bat call went out. And a pint sized kid crusader arrived in the bat mobile. It's bat kid. Bat kid to the rescue. While an estimated 13,000 people gathered to cheer him on. The mini super hero has battled evils before. Behind the mask is five-year-old miles scott, a leukemia survivor from tulelake, california, diagnosed at 18 months, just finished his last chemotherapy treatment in june. And had an ambitious dream. Be batman. Reporter: The make a wish foundation made it happen. Thousands respond and set up fake crimes for miles to solve like the riddler robbing a nearby bank. Batman and bat kid went to the scene to take on their arch enemy. There have been plenty of super hero wishes over the years, nothing like this has happened. This is far beyond any of our expectations, it's crazy how big it's gotten. Reporter: The out pouring here has been tremendous, there are tens of thousands of onlookers. The police chief had to turn away volunteers. It's so inspiring. Reporter: Bat kid got the key to the city made of chocolate, the super hero's favorite. Bat kid. Bat kid. Reporter: He also conquered the hearts and minds of people around the world. Aditi roy, abc news, san francisco. And one more note, if you take a close look at the front page of today's gotham city chronicle, the by lines were from those veteran journalists, clark kent and lois lane. Somewhere super man cheering him on.
This transcript has been automatically generated and may not be 100% accurate.