Humberside Police is investigating after it happened overnight at Bridlington Police station, with abusive emails sent to the Chief Constable, the Police and Crime Commissioner and the chair of the Hull and East Riding LGBT Forum, Andy Train.
It was the first time Humberside Police had flown the rainbow flag - a symbol of pride and diversity - from its buildings and the flag was pulled down and then removed from the site.
A group calling themselves Men of Bridlington claimed to have done it.
Mr Train received an abusive email in the early hours of yesterday, and said: “I spoke to Humberside Police and straight away they said it is a hate crime and that I was not to forward it. It’s shocking. It’s as if you had some bigot from the 1950s and planted them in Bridlington. I suspect the person that did this has a lot of personal issues.”