Twitter was used (and not a presidential alert) to warn people about an active mass shooting: https://www.cbc.ca/news/canada/nova-scotia/rcmp-twitter-alert-mas

Twitter was used (and not a presidential alert) to warn people about an active mass shooting: https://www.cbc.ca/news/canada/nova-scotia/rcmp-twitter-alert-mass-shooting-portapique-nova-scotia-1.6477095 https://www.cbc.ca/news/canada/nova-scotia/rcmp-twitter-aler...