A man who claimed he found the subject disturbing put his foot through a 17th-century painting valued at $300,000 at the Milwaukee Art Museum.
The oil painting depicts the end of the biblical tale of David and Goliath, with David carrying the severed head of the giant Goliath, Gordon said.
"[The man] was kicking it, aiming his blows at the head of Goliath, and then he pulled it off the wall and started kicking it," Gordon said.
"It happened very quickly. We have guards constantly on patrol in the museum, and he obviously waited until the guard had passed through that gallery," he said.
A museum employee and security guard tried to restrain the man, and eventually he stopped, took off his shirt and lay on the gallery's floor, Gordon said.
The 22-year-old Pewaukee man told police he was disturbed by the image of Goliath's severed head.