New York City police are investigating the circumstances surrounding a severed horse head in a box found in a Manhattan park.

New York City Police Department Public Information Office Detective Martin Speechley said police personnel responded to a call from a woman who reported finding a sealed box displaying Corona beer logos in Manhattan’s Highbridge Park on Feb. 28. Inside the box was the severed head of a horse, Speechley said. The box also contained a goat head, as well as fruit and vegetables.

“One theory is that the contents of the box were part of a ritual,” Speechley said.

He declined to comment further