A baby gorilla was killed at a San Francisco zoo when a closing hydraulic door trapped her underneath its path, the LA Times reported on Saturday.

The 15-month-old female lowland gorilla, Kabibe - or "little lady" in Swahili - ran under the closing door when zoo crew members were moving animals into their nighttime areas, according to a news release.

"Some animal deaths are more difficult to process than others, and this tragedy has struck us all in the deepest way imaginable," San Francisco Zoo Executive Director and President Tanya Peterson said, according to NBC.

Born on July 17, 2013, Kabibe needed around-the-clock care for six months after her birth, leaving some zoo workers grieving over her death since they became attached to her from the unusual amount of early bonding time.

She was one of the few gorillas born in captivity in the United States and was even rejected by her mother at birth. 

Some animal rights activists are bothered by the incident, which they say could have been prevented with better safety measures. In Washington D.C. and Canada, there have been other animal deaths caused by hydraulic doors in the past few years.

An alternative to the doors could be one where zoo staff members would be able to push a button to change the door's motion or stop it completely, according to Elliot Katz, a veterinarian and founder of In Defense of Animals.

Kabibe's old home at the Jones Family Gorilla Preserve will stay open following her death. 

The young gorilla's fans were sad to hear the news of her passing. Denise and Michael Henley brought their two young grandchildren to see the animals at the zoo. Michael Henley said he became concerned when he didn't see Kabibe at all after waiting for 10 minutes.

"To have a door slam on her is devastating," Henley said. "You want to see them get bigger and bigger and grow up."