SAN FRANCISCO-A five-year-old boy recovering from cancer became a superhero for a day Friday, as San Francisco transformed itself into Gotham City and thousands turned out to see the Batkid fly to the rescue. Even President Barack Obama got in on the act after the story went viral, sending pint-size caped crusader Miles Scott a video message telling him “Way to go!”

Scott, who was diagnosed with leukemia when he was 18 months old, was cheered as he roared out in his Batmobile to nab arch-villain Riddler and save a damsel in distress tied to the city’s famous tram tracks. Police chief Greg Suhr ordered his men to help the diminutive crime-fighter take on his nemesis the Penguin, while he also got messages from San Francisco’s baseball and NFL teams for his day in the limelight.

“Our hero has arrived. The streets of San Francisco are safe today” the San Francisco 49ers tweeted, as social media went wild for the youngster, prompting huge crowds to follow him. The story then took off, making national and international news, with live coverage by outlets including CNN. “I’ve never seen anything go viral like this, with the outpouring of support from across the world,” said Patricia Wilson of Make-a-Wish Foundation, the charity which organized the dream day.  Thousands gathered in the city’s Union Square when the Batkid took a break to refuel at a local restaurant. “Even superheroes have to have lunch,” explained one TV reporter, surveying the throng stretching across the square. The city’s San Francisco Chronicle printed a special edition for, with a “Gotham City Chronicle” masthead and a screaming headline: “Batkid Saves City!” The US Attorney’s office put out a spoof press release - datelined “San Francisco/Gotham” - announcing that the Riddler and the Penguin had been charged with conspiracy and kidnapping.