Officials at Utah's Hogle Zoo say they've launched an investigation into the deaths of two Grevy's zebras.

Officials said Thursday that zookeepers found the first animal, Taji, dead in his exhibit area Tuesday. A necropsy conducted that day identified no obvious cause of death.

Staff found the second zebra, Monty, in distress and began treatment Wednesday. He was later euthanized.

Associate Director of Animal Health Dr. Nancy Carpenter says staff is now consulting with other veterinary experts to determine what caused the deaths. The U.S. Department of Agriculture has been invited to participate in the investigation.

Taji and Monty came to Utah to a Wichita, Kan., zoo in 1998. Grevy's zebras are native to Africa and are considered endangered.

Taji was born in 1995 and Monty in 1997.