Zuckerberg in a statement Wednesday that he will investigate access to data about users that are currently available to outside developers of Facebook-friendly apps.

“We will learn from this experience to secure our platform further and make our community safer for everyone going forward,” Zuckerberg wrote.

Cambridge Analytica, a company launched by former Trump adviser Stephen Bannon and bankrolled by the Republican donor Robert Mercer, is alleged to have improperly received data on potential voters from a researcher and app developer who had violated Facebook policy.

Over the weekend, news outlets reported that the user data collected were reportedly used to influence the vote in the 2018 presidential election. The Trump campaign reportedly paid Cambridge Analytica more than $6 million, according to federal election records.

Following the reports, Facebook’s stock took a hit, and American and British lawmakers called on Zuckerberg to testify in front of various government committees.

On Wednesday, Zuckerberg said that in addition to investigating other applications created before 2014, when it tightened its data-sharing policy, the company would also take steps to limit the data other apps could access and launch a tool to show users what apps have access to their data. Outside makers of various games, quizzes and other tools often collect reams of data on users, which they are ostensibly prohibited from sharing with third parties.

“We have a responsibility to protect your data, and if we can’t then we don’t deserve to serve you. I’ve been working to understand exactly what happened and how to make sure this doesn’t happen again,” he said.

Cambridge Analytica CEO Alexander Nix, since suspended, also bragged to an undercover reporter posing as a potential client that the company used Israeli companies and former Israeli spies in its intelligence gathering. The report, aired by Britain’s Channel 4 on Monday, did not connect the Israeli companies with the reported Trump operation.