Facebook CEO Mark Zuckerberg apologized to US lawmakers on Tuesday, telling a Congressional hearing that the company had not done enough to prevent the misuse of user data.

Zuckerberg made the comment during the first of two highly anticipated hearings on Facebook's involvement in the Cambridge Analytica scandal.

What Zuckerberg said:

• "It was my mistake, and I'm sorry. ... I started Facebook, I run it, and I'm responsible for what happens here."
• "It's clear now that we didn't do enough to prevent these tools from being used for harm. ... That goes for fake news, foreign interference in elections, and hate speech, as well as developers and data privacy."
• "It will take some time to work through all of the changes we need to make, but I'm committed to getting it right."
• Facebook is working with the special investigation into Russian meddling in the 2016 US presidential election. "There are people in Russia whose job it is to try to exploit our systems and other internet systems and other systems, as well. ... This is an arms race. They're going to keep getting better, and we need to invest in getting better at this, too."

Read more: Facebook chief Mark Zuckerberg admits responsibility for data misuse

The scandal: In March, a whistleblower revealed that Cambridge Analytica, his former employer, had gained access to the personal data of millions of Facebook users without their knowledge. The company used the information to influence the 2016 US presidential election and the 2016 Brexit referendum. On Tuesday, Facebook announced that it had started notifying some of the 70.6 million users in the US and around 2.7 million users in the European Union who were affected.

Legal consequences: Facebook has been heavily criticized for allowing the breach and faces two federal lawsuits — one in California and one in Delaware — over its handling of user data.

Read more: What role did Cambridge Analytica play in the Brexit vote?

Facebook's 'bounty': The company has promised to shore up its safeguards for user data. On Tuesday, it announced a "data abuse bounty" to "reward people with firsthand knowledge and proof of cases where a Facebook platform app collects and transfers people's data to another party to be sold, stolen, or used for scams or political influence."

Read more: Facebook to notify users affected by Cambridge Analytica scandal

Who is Mark Zuckerberg? The 33-year-old has been Facebook CEO since he founded the company in 2004 as an undergraduate student at Harvard University. Forbes magazine estimates his personal wealth at about $66 billion (€53 billion).

Read more: Facebook: German justice minister vows stricter regulations

One of two: Tuesday's joint hearing before the Senate's commerce and judiciary committees was the first of two Congressional appearances for Zuckerberg. He is set to testify at a second hearing on the scandal on Wednesday, before the House Commerce and Energy Committee.

amp/jm (dpa, Reuters, AP, Reuters)
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