A homeowner set up a music desk in their living room then tried to hide five guests when police arrived.
Officers were called to an address in Runcorn, Cheshire, after neighbours reported hearing loud music, the Liverpool Echo reports.
Tier 3 coronavirus restrictions were imposed on the Liverpool City Region, which includes Runcorn, meaning that mixing between households is banned.
But police reported all six people in the house had 'blatantly' breached the rules.
They issued all of them with £200 fines.
Cheshire Police said in a statement on their Facebook page : "We don’t want to stop you from enjoying yourselves but we really need you to stick to the rules so that we can help reduce the spread of the virus.
"Whenever there is a breach we will always engage, explain and encourage people to follow the rules but sometimes, no matter how hard we try, we have to enforce.
"Last night we visited an address in Grangeway, Runcorn following reports of loud music.
"When we entered the house the owner had set up a music desk in their living room and was busy trying to hide five guests.
"Everyone at the house said they were aware of the rules, but still attended anyway.
"As a result of this blatant breach all six people were issued with £200 fines."
The force added: "Over the weekend it’s been really encouraging to see that the majority of residents across Cheshire have been sticking to the rules and are doing all they can to slow the spread of Covid-19.
"Disappointingly there are a small number of people who are breaching them."