Thousands of pounds worth of games consoles and televisions were stolen Carlisle United's ground.
The equipment was taken overnight on Saturday from the family zone in the Pioneer (East) Food Stand.
The club, which said it was "devastated", said an individual forced entry into the ground through the Stoneyholme Golf Club entrance.
A spokeswoman said it had caused a "lot of distress" and had taken away something which "so many people enjoy".
The theft is believed to have lasted more than four hours.
Finance director Suzanne Kidd said: "We're absolutely devastated that someone would do this to such an important part of our club.
"There are no words to describe how we feel about that. We're working with the police to do everything we can to make sure this person is apprehended."
The club said the area would remain closed until further notice, including for their home game against Stevenage.