A prank call disrupted services at Denver Zoo on Tuesday.

Just before noon, a person called the zoo and said he was being chased by a “large animal with large teeth.”

The call triggered a Code Red alert, meaning zoo staff closed all the gates to the zoo and moved visitors into buildings like Tropical Discovery and restaurants.

After searching each enclosure, zoo staff determined that all animals were accounted for.

Operations have since returned to normal.

Denver Zoo says pranks like this waste resources and panic guests. 

The zoo is working with the Denver Police Department on tracking down the person who made the call.