Police in Cleveland in the US are searching for a man who showed the fatal shooting of a random victim live on Facebook.
The suspect, Steve Stephens, later said in a separate video post that he had killed 13 people and was looking to kill more.
Cleveland police confirmed one killing but said they did not know of any other victims.
It is not the first time that a fatal shooting has been captured on Facebook Live.
Last June, a man was shot dead while live‑streaming a video of himself on the streets of Chicago.
In March this year, an unidentified man was shot 16 times while broadcasting live.
Facebook's live‑streaming feature allows anyone to broadcast online in real time.
It was launched in 2010 but has become more central to the social network's strategy in recent months.