"Hi this is an automated message from Facebook alerting you that the police have been called to your husband's/friends/boss's location to prevent him from killing himself"
"Actually just kidding, we had a little SNAFU. Thank you for being a loyal Facebook user, we assume this had a neutral effect on your life"
Actually Instagram does send a message to the user if enough people mark the user in danger of being harmed. Similar with Google where if someone searches for methods of committing suicide the user will get a number for helpline as first result in bold letter.
"Actually just kidding, we had a little SNAFU. Thank you for being a loyal Facebook user, we assume this had a neutral effect on your life"