Facebook now has 1.8 billion users, but not all of them are using it for good.

Social media pioneer Mark Zuckerberg addressed that fact today at the company’s annual developer conference.

Zuckerberg’s remarks at the event were about the future of technology at Facebook.

But in light of a tragic murder in Cleveland Sunday, the CEO felt he had to make a statement.

The suspect—Steve Stephens—allegedly shot an elderly man in the head, then uploaded the video on to his Facebook page, where it stayed for several hours.

Similar incidents have been posted on Facebook before.

So while the company is battling a problem like fake news, it also has deadlier issues to face.

Zuckerberg says Facebook will keep working on ways to prevent such tragedies.

"We have a full road map of products to help build groups and community... help build a more informed society... help keep our communities safe,” he said.  “And we have a lot more to do here. And we're reminded of this, this week, by the tragedy in Cleveland. And, our hearts go out to the family and friends of Robert Godwin Sr.. And we have a lot of work and we will keep doing all we can to prevent tragedies like this from happening."