Two families got into a confrontation at the park just before 5 p.m. Sunday, according to a park spokesperson.
Park Safety responded to the scene and called in police and first responders.
The victim, 47-year-old James Burns, was taken to an area hospital in serious condition.
Daniel Tomasky, 42, was arrested.
He's now facing charges of assault, criminal possession of a weapon, and endangering the welfare of a child.
Tomansky is set to appear in First District Court in Central Islip on Monday for his arraignment.
The park remained open after 8 p.m. once the scene was processed.
A statement from a park spokesperson reads in part,
"For more than 60 years, Adventureland has been providing Long Island families with a convenient, affordable and fun local destination. The safety and security of our visitors is our highest priority."
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