A British radio station pleaded guilty Friday to injuring four listeners who suffered severe frostbite after sitting on dry ice for a competition.

After the “Coolest Seats In Town” challenge by BRMB radio in Birmingham, the participants — aged between 15 and 30 — had to be hospitalized and suffered scarring.

“We pleaded guilty and have been fined 15,000 pounds ($25,000),” a spokesman for BRMB told Reuters.

The Health and Safety Executive, the safety watchdog which brought the prosecution, said the temperature of the dry ice — frozen carbon dioxide — was minus 108.40 degrees Fahrenheit.

The prize for the contest held in August 2001 was tickets to a music festival called “Party in the Park.”

The radio station said it was sorry about what had happened.