Zoo spokeswoman Tonja Candelaria says the Eastern Bongo, called Ferdinand, was being treated for suspected pneumonia when he died.
The zoo says in the wild, the antelope is found mostly in lowland forests of Kenya. It's estimated that fewer than 250 individuals are left in the wild.
The antelopes are chestnut colored, with white body stripes, banded legs and two spiral horns.
Ferdinand was born in 2009 at a zoo in Texas and came to the Sacramento Zoo in 2012.
“One of the kids’ most favorite things to do during our summer camp is to go behind the scenes and feed carrots to our majestic bongo," said Ann Geiger, Education Director at the Sacramento Zoo, in a news release. "Our animals provide so many wonderful memories and stories that children will take with them long after they have visited the Zoo. Our Bongo will be missed by young and old alike.”
The zoo said Ferdinand was a gentle and calm Bongo, popular with visitors and adored by Summer Camp kids.