MASON (AP) — A man who apparently entered a restricted area to retrieve his lost keys at Kings Island was critically injured when he was struck by a steel roller coaster, police and park officials said.

The 38-year-old man appeared to have entered a fenced area at the amusement park Wednesday night, according to a statement issued by the park near Cincinnati. Police identified the man as Arntanaro Nelson, according to WLWT. He was taken to the University of Cincinnati West Chester and then flown to UC Medical Center. Police said the man suffered critical injuries.

The man dropped his keys while riding the Banshee, an inverted roller coaster where the train dangles from the track, and then went into the restricted area and was struck by the coaster, according to Mason police.

According to the park’s website, the Banshee is the world’s longest steel inverted roller coaster and reaches speeds of 68 mph (109 kph).

The roller coaster was shut down and will remain closed while the investigation continues. No other injuries were reported.

The park is in Mason, which is about 24 miles (38 kilometers) northeast of Cincinnati.