Muskegon County Sheriff Dean Roesler said the gas was created by the release of a combination of chemicals at Michigan's Adventure.
Twenty-seven people were taken to two area hospitals. WZZM-TV reported that the victims suffered respiratory discomfort and a burning sensation in their eyes.
At least 25 people were showered off in the park's parking lot.
A hazardous materials response team, paramedics and firefighters were called to the park.
Michigan's Adventure is the state's largest amusement and water park.