Several people were sickened by carbon monoxide fumes Saturday evening at the Wintersport Ice Sports Arena in Hatboro.

After a game of ice hockey, as the Zamboni smoothed the ice, about a dozen people in the arena began to fall ill and emergency personnel were called, according to authorities at the scene.

Many of the sick began to feel better after stepping outside into the the fresh air, but five victims with lingering "low-grade dizziness" were taken by the Second Alarmers Rescue Squad to Abington Memorial Hospital to be treated, Fire Marshal Robert Drennen said.

Fire crews from Upper Moreland and Abington entered the arena and discovered carbon monoxide levels reading 300 parts per million - well above safe levels, according to Drennen.

Officials are investigating the cause of the high levels of carbon monoxide and believes fumes from a malfunctioning oil-fueled water heater could be the source. The heater will remain shut-off until it can be serviced by maintenance personnel, Drennen added.

"There were running-vehicles outside and the Zamboni inside, which could have contributed, but it is more than likely it was the water heater," Drennen told Patch.

Firefighters ventilated the building and declared it safe to reopen shortly before 8:30 p.m. about an hour and a half after the initial call came in.