A woman, Marta Sala Font, heard some noise over her house at 2am, so she tweeted at the Metropolitan police: "Why are u flying over east london at 2am? It's completely unnecessary to b that noisy at this time. I doubt u can see anything!"
In the reply, the MPS Helicopters account included a full stop before their tweet, making it appear in the timeline for their 91,000 followers.
So people started to reply. First, she was accused of being ignorant.
And then the mood changed.
And then Marta decided to leave Twitter after two years, probably because of the abuse she got.
But this isn't the only time this has happened. Sarah Buckley wrote a sarcastic tweet just before midnight when she heard the helicopters in the sky.
The Met's response, again, was public, and generated over 500 retweets. It was also retweeted by six other official police Twitter accounts.
And so the pile-on began.
When asked whether the force was acting irresponsibly, the Met said of Marta: "Well, maybe they decided that social media was not for them."
H/T to Anya, who compiled this here.