A northern white rhinoceros died at a zoo in California on Sunday, leaving just five of the rare rhinos left in the entire world.

Officials at the San Diego Zoo Safari Park said Angalifu, the rhino, died at about 44 years old after being treated for issues stemming from age, U-T San Diego reported.

"Angalifu's death is a tremendous loss to all of us," Randy Rieches, curator of the safari park, said in a statement. "Not only because he was well beloved here at the park but also because his death brings this wonderful species one step closer to extinction."

Angalifu arrived at the zoo in August from the Khartoum Zoo in Sudan. His death comes after another northern white rhino died in Africa in October.

There are now three northern white rhinos at a preserve in Kenya, along with one at a Czech zoo and a female named Nola at the same San Diego zoo, the Associated Press reported.

Wildlife officials tried to mate Angalifu with Nola and other rhinos but attempts were unsuccessful.

"Unfortunately we only had three rhinos here at the park and they were all of an advanced age," Barbara Durrant of the San Diego Zoo Institute of Conservation Research said according to U-T San Diego. "We were not able to get them to breed and we have been sadly watching their species being exterminated in the wild."

Officials also hoped the wildlife surroundings of the preserve in Kenya would help increase their numbers but that too proved unsuccessful, the AP reported.

The rhinos have been brought to the brink of extinction due to poachers that go after their horns, which are then used as aphrodisiacs or for dagger handles. The only hope of reviving the species now appears to be through in vitro fertilization, thanks to experts who were able to preserve Angalifu's semen.