« Facebook has now developed pattern-recognition algorithms to recognise if someone is struggling, by training them with examples of the posts that have previously been flagged.Talk of sadness and pain, for example, would be one signal.Responses from friends with phrases such as « Are you OK? » or « I’m worried about you, » would be another.Once a post has been identified, it is sent for rapid review to the network’s community operations team ».

Source : Facebook artificial intelligence spots suicidal users – BBC News