At the TechCrunch Disrupt event in San Francisco today, Facebook CEO and co-founder Mark Zuckerberg told Michael Arrington of CrunchFund one major new figure: Instagram has passed 100 million users. “[Instagram] just crossed 100 million users,” Zuckerberg said. “They’re killing it.”

This has never been revealed before and may have been a slip-up from the young CEO. Zuckerberg also reiterated that he wants to help the app grow, but at the same time he doesn’t want to meddle with it.

“Our mission around Instagram is we think Instagram is amazing, and we want to help it grow to hundreds of millions of users,” Zuckerberg also said. “We want to help them out with whatever we can. We have no agenda in terms of making them go into our infrastructure. We’re just going to do the things that we would have done if they were an Open Graph partner, but now we can prioritize them more highly. They can do a lot directly, because they have access to our code directly.”

Facebook announced its plans to acquire Instagram in April 2012. The company only closed the deal last week, however, as the FTC gave the green light just three weeks ago. When Facebook announced everything was final on September 6, Instagram revealed it had passed the 5 billion photo milestone.

Back in late July, Instagram passed 80 million users, growing at a rate of more than 10 million users on average per month. When Facebook closed the acquisition, I wrote “If that trend continues, we can expect the 100 million user milestone any day now.” It appears that I was right, but even I didn’t think Zuckerberg would be the one to reveal the milestone.

There are currently two rumors going around as to Instagram’s future. The first is plans to port Instagram to the Web. The second is a Windows Phone app, slated for release later this year.

Facebook and Instagram won’t comment on those rumors, but I have contacted the two companies to confirm the new 100 million user number. I will update you if and when I hear back.

Update: A Facebook spokespersons confirmed to The Next Web that the 100 million user statistic is accurate.

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