Updated

Montgomery Zoo officials in Alabama say they're trying to determine what led to the death of a baby Indian rhinoceros. The animal was found dead at the zoo Friday.

The 4-month-old rhino, Ethan, was named after Ethan Gilman, the Alabama boy rescued from a bunker by an FBI hostage rescue team after a six-day standoff in southeastern Alabama in February.

Cincinnati Zoo officials had called Ethan the first known rhino calf in the U.S. to be produced by artificial insemination and to survive and thrive in captivity. The Cincinnati Zoo worked with the Montgomery Zoo to make the birth possible.

Montgomery Zoo spokeswoman Sarah McKemey tells The Montgomery Advertiser that nothing obvious was wrong with the rhinoceros before his death. She said the death was "sudden and unexpected."

WAKA-TV reports that a necropsy is planned.