Facebook CEO Mark Zuckerberg broke his silence over a burgeoning scandal Wednesday, telling CNN he’s sorry that his company allowed a voter-profiling company named Cambridge Analytica to harvest the data of more than 50 million Facebook users, without their permission, in efforts to sway voters to support President Donald Trump.

Mark Zuckerberg: “So, this was a major breach of trust, and I’m really sorry that this happened. You know, we have a basic responsibility to protect people’s data, and if we can’t do that, then we don’t deserve to have the opportunity to serve people. So, our responsibility now is to make sure that this doesn’t happen again.”

Zuckerberg’s apology came days after CBS reported that Facebook knew about Cambridge Analytica’s data harvesting two years ago but failed to report the practice to users. Cambridge Analytica was founded by billionaire Robert Mercer. Trump’s former adviser Steve Bannon of Breitbart News was one of the company’s key strategists.