Zuck has finally spoken.

Almost a week after reports that Cambridge Analytica — a data analytics firm that did work for Donald Trump's presidential campaign — illicitly obtained Facebook data for up to 50 million users, CEO Mark Zuckerberg addressed the scandal in what else but a Facebook post.

“I've been working to understand exactly what happened and how to make sure this doesn't happen again,” Zuckerberg wrote. He acknowledged that the company “made mistakes” and that “there's more to do, and we need to step up and do it.”

Zuckerberg laid out his understanding of events and then pledged three changes to the platform to prevent more Cambridge Analytica-type situations in the future.

The company will audit all app developers that collected user data before 2015, when Facebook began restricting access to data from friends of the user. Cambridge University researcher Aleksandr Kogan had gathered user data using a psychological personality quiz on the social network before the changes were made. He then sold the data to Cambridge Analaytica. Zuckerberg said the company would ban any developer that did not consent to the audit, but it's not clear what the company will do for developers that are no longer active on Facebook and may have already sold off the data they collected.

Facebook will stop developers from gathering user data if the user hasn’t been using the app for three months.

Facebook will make it easier for users to remove apps and revoke access to their data from apps within the next month. The company will roll out a tool bar at the top of the news feed with the list of apps that currently have access. At the moment, it’s difficult to remove apps because the option is partially hidden in the site’s privacy settings.

Beyond the serious questions about data security, Trump’s campaign also paid Cambridge Analytica $5.9 million to be one of its top consulting groups during the election. That suggests Cambridge Analytica may have used the purchased user data to better target its social media advertisements, a factor in Trump’s victory over Hillary Clinton.

Before his post on Wednesday, Zuckerberg had remained on the sidelines of the scandal, even though Facebook is set to brief state attorneys general and staffers on Capitol Hill on Thursday. Lawmakers at the state and federal level have been extraordinarily critical of the company over the last few weeks. Some state attorneys general have begun looking into whether the company broke state privacy laws.

“Attorneys General Healey [of Massachusetts] and Schneiderman [of New York] have raised several important questions,” Will Castleberry, Facebook’s vice president of state and local policy, said in a statement. “We appreciate their attention to this matter and look forward to responding.”

Lawmakers in D.C. of both parties have also been irate. Some have even called for Zuckerberg to personally testify in front on Congress, which the company has avoided in past controversies. Most recently, Facebook’s general counsel Colin Stretch was the one to testify to multiple committees investigating how Kremlin-linked Russians purchased political ads during the 2016 election.

Still, the Cambridge Analytica scandal has set off a political firestorm unlike anything the company has ever faced.

Facebook failed to notify tens of millions of people whose user data was compromised after the company discovered that Cambridge Analytica had bought the information. Instead, Facebook worked with Cambridge Analytica to push users to quietly delete their data. Copies of at least some of the data still exists, though, The New York Times and The Observer of London reported.

After reporters notified Facebook that copies of the data still existed, the company announced it had suspended Cambridge Analytica from using the platform.

Facebook COO Sherly Sandberg shared Zuckerberg’s post and added, “We know that this was a major violation of people's trust, and I deeply regret that we didn't do enough to deal with it.”

Zuckerberg is expected to further address the issue on CNN on Wednesday night at 9 p.m. ET.

As the CEO said in his status update, “I started Facebook, and at the end of the day I'm responsible for what happens on our platform.”