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USA TODAY

5-year-old Miles Scott was diagnosed with leukemia when he was 18 months old

7%2C000 people have been involved in making his day

Make-A-Wish has fulfilled similar wishes across the country

SAN FRANCISCO — The day dawned blue and warm. Perfect weather for a robbery. Or so the Penguin thought.

Saving the day while raising the spirits of a major U.S. city was pint-sized Miles Scott, 5. Miles is in remission from leukemia, and, thanks to the Make-A-Wish Foundation, managed to turn his obsession with comic book heroes into the real thing. Well, almost. There was no way Penguin was going to get away with anything on Friday.

Thousands of San Franciscans responded to an avalanche of social media blasts, lining the streets wherever Miles and a full-sized Batman swooped into action. At Hyde and Green streets, there was a damsel in distress to rescue, and the bat duo arrived in a Lamborghini with Batman decals. At 550 Montgomery St., a burgled bank vault needed to be liberated. And at Union Square, there was a hamburger to down.

"This just restores your faith in humanity," said Carmen Kiew, 30, a sports blogger who sat on the steps of Union Square with a handmade sign that read "Gotham's Hero."

"I love that this city came together for a little kid who has been so brave," Kiew said. "Between the police and everyday citizens who felt it was important to show their support, it just makes you feel great."

Behind Kiew, thousands of citizens of Gotham-for-the-Day held up camera phones as they awaited the bat-eared duo's arrival. The bat pair took a lunch break inside Macy's before heading to AT&T Park to foil the Penguin once and for all, and then — of course — would show up at City Hall to get the key to the city from San Francisco Mayor Ed Lee.

Every other T-shirt on Friday seemed to sport the famous Batman logo in support of Miles; some were simply hand-drawn with markers, while others were official Batkid tees, which were sold by uniformed police officers at $20 a pop, with all proceeds going to the Make-A-Wish Foundation.

"That poor little kid," said Daniela Vilchis-Lent, 18, who came from Oakland with five relatives, some as young as 2, to cheer Batkid on. "If my taking a little time to be here helps him, then I'm glad to do it."

By all accounts, the groundswell of civic support even caught Make-A-Wish by surprise. When a local social marketing company reached out a few weeks ago, asking what the foundation's plan was to spread the word about Miles, "They honestly didn't have a plan and were happy for the help," says Stefania Pomponi, founder of the Clever Girls Collective.

Pomponi and her staff promptly contacted Twitter, which provided the @SFBatKid handle. Then things blew up, in the way that online viruses can.

"It wasn't long before we were getting e-mails and tweets from all over the world, people saying that they were so glad they could participate in this event thanks to social media," said Pomponi. "It's been amazing. It's truly developed a life of its own."

Miles, who lives in Tulelake in far Northern California, was diagnosed with leukemia when he was 18 months old, ended treatments in June and is now in remission.

His father, Nick Scott, thanked the Greater Bay Area Make-A-Wish Foundation and the estimated 7,000 people who were helping make his son's wish come true.

"All the doctors, nurses and all the other parents that have to deal with the same thing we're going through. I hope they get a conclusion to their illnesses like we're getting," Nick Scott told KGO-TV.

Make-A-Wish has fulfilled similar wishes across the country. In Anaheim, a child became Batman's sidekick, Robin; and in Seattle a child was a secret agent, said Jen Wilson, a spokeswoman for the local organization.

By the time Batkid, wearing a movie-ready mini-Caped Crusader costume, showed up at City Hall after saving San Francisco Giants mascot Lou Seal from the clutches of his nemesis, the gathered masses could not contain their excitement. Thousands roared as Scott made his up onto a platform; his even smaller brother was, fittingly, dressed as Robin. Everywhere, nothing but a sea of people with arms raised, cell phones in hand.

"Today, November 15, 2013, is Batkid day forever," said Mayor Lee, as Scott chomped away on gum in front of a faux front page of the Gotham City Chronicle, whose headline blared, "Batkid Saves City". "You won our hearts with your story ... it's been a day of magic."

The mayor then cautioned Batkid that even though he'd soon be returning to his home, "we might need to have to signal for your help."

A little recuperation might be in order first. A planned interview with Batkid was scotched at the last minute, with a member of the Batkid retinue explaining that the five-year-old was hitting his wall. It seems even superheroes need a nap.

The Associated Press contributed to this article.