Kabibe, a 15-month-old western lowland gorilla, was killed Friday when she darted under a closing hydraulic door at the San Francisco Zoo.

The fatal accident occurred after-hours when the zoo's gorillas were being transferred from their main enclosure to their night quarters, NBC News reports.

"Some animal deaths are more difficult to process than others," said a zoo spokesperson in a statement, "and this tragedy has struck us all in the deepest way imaginable."

According to the San Francisco Chronicle, at least two other animals have been killed in incidents involving hydraulic doors at zoos.

[Image via Facebook/May Woon]