City officials closed the Long Beach Ice Arena for several hours Wednesday after youth hockey players reported feeling sick during the previous night’s practice.

Firefighters then found elevated carbon monoxide levels — in some areas, as high as seven times safe levels — that kept the city-owned arena closed until repairs could be made to a malfunctioning water heater, Nassau County officials said.

The malfunctioning water heater was disabled.

Long Beach Fire Commissioner Scott Kemins said he was notified Wednesday morning players on a youth hockey team were nauseous and vomiting Tuesday night after practice.

The county fire marshal’s hazmat team responded to the arena on West Bay Drive after a call by the Long Beach Fire Department at 9:45 a.m., Assistant Chief Fire Marshal Michael F. Uttaro said.

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Officials delayed opening the arena as fire marshals, Long Beach firefighters and workers with National Grid inspected the building and tested carbon monoxide levels.

Firefighters turned off all appliances and ventilated the building while each individual appliance could be tested.

The building reopened Wednesday afternoon.

County fire officials said the building does not have CO alarms — and said the fire marshal’s office has requested alarms be installed.

No one was hospitalized, but city officials contacted the coach of the hockey team and urged players feeling any lingering effects to contact their physicians.