The zookeeper who was bitten by a zebra at the National Zoo last month broke protocol by leaving open the doors from the zebra’s barn to the holding area, allowing the animal to enter the holding area and attack him, an investigation into the incident found.

“The animal management protocol states that humans and dangerous animals, such as a Grevy’s zebra, should never be in the same space together,” a summary of the report stated. “There was no other witness to inform the inspection team as to how the zebra and keeper ended up together. The zebra should have been contained in his primary stall while the keeper was cleaning the adjoining stall.”

The zookeeper was seriously injured. The zoo has been monitoring the zebra, Gumu, since the incident and says it has not noticed any unusual behavior.

A 1-year-old gazelle that witnessed the biting died as a result of the violent incident when he became spooked and ran into a barrier.

Photo by James F Clay via Flickr/CC BY-SA 2.0