An arena on Brookside Drive was evacuated Thursday night after at least a dozen people began showing symptoms of carbon monoxide poisoning.

Two men’s league teams were playing at the London Ice Park on Brookside Dr. around 7:30 when several of them started feeling sick, about an hour and a half into the game.

One person was taken to hospital for treatment, while paramedics assisted several others at the scene.

Members of the London Fire Department’s hazmat team went through the twin-pad building, and did uncover elevated levels of carbon monoxide.

The exact source of the potentially deadly gas wasn’t immediately clear.

via AM980 News