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Mark Zuckerberg spoke publicly for the first time on Tuesday about the Cleveland murder video that stayed up on Facebook for nearly two hours before it was removed.

Taking the stage one hour after suspect Steve Stephens apparently shot and killed himself in Pennsylvania, the Facebook CEO told the crowd of developers, analysts, and reporters that Facebook has more work to do in making its 1.86 billion strong community safer.

"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," Zuckerberg said.

He then pivoted, diving into the agenda for the annual two-day conference, which is taking place in San Jose, California.

On Monday, Facebook's vice president of global operations, Justin Osofsky, said they were "reviewing our reporting flows" following the Easter Sunday tragedy.

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Related: Cleveland Shooting Highlights Facebook’s Responsibility in Policing Depraved Videos

In addition to posting a video of the murder, Stephens also went live twice, the first time announcing his intent to kill — and the final time, after the murder, confessing.

Facebook wasn't made aware of a live video containing Stephens' confession until after it had ended, Osofsky said. The initial video in which Stephens shares his intent to murder was never reported, according to Osofsky.

"We disabled the suspect's account within 23 minutes of receiving the first report about the murder video, and two hours after receiving a report of any kind," Osofsky said. "But we know we need to do better."

He shared the following timeline of events of how the Easter tragedy unfolded on Facebook.

11:09 a.m. PT — First video, of intent to murder, uploaded. Not reported to Facebook.

11:11 a.m. PT — Second video, of shooting, uploaded.

11:22 a.m. PT — Suspect confesses to murder while using Live, is live for 5 minutes.

11:27 a.m. PT — Live ends, and Live video is first reported shortly after.

12:59 p.m. PT — Video of shooting is first reported.

1:22 p.m. PT — Suspect's account disabled; all videos no longer visible to public.