There was a serious fire in London this week. People in the area received Facebook push alerts saying "The fire in London, United Kingdom" with a button that said "Tell friends that you're safe."
A lot of people seem to not like the notifications, though. The sense is they are "uncomfortable" with them and that the notifications might add to peoples' stress to drive engagement. Also, the notifications rely on Facebook's geolocation, which isn't very accurate, so people 100's of miles away sometimes got the notification.