CHICAGO (CBS) —  Early results show a nine-day-old baby gorilla at Lincoln Park Zoo died overnight from head trauma.

Zoo pathologists have found a skull fracture, zoo spokeswoman Sharon Dewar tells WBBM Newsradio’s Nancy Harty.

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“We don’t know exactly what happened to it, but definitely the cause of death seems to be a head injury,” she said Friday.

LISTEN: WBBM Newsradio’s Nancy Harty reports

Dewar says zoo officials had been closely watching the baby and mother since the Nov. 16 birth, knowing the newborn was vulnerable.

“They still have a soft skull, just like a human infant would. They’re at risk for injury,” Dewar said.

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Full necropsy results were expected in a few weeks. The gorilla exhibit will reopen Saturday.

Zoo workers found the baby dead on Friday morning. The baby was being carried around by her mother. Workers let the mother, 16-year-old Bana, keep the baby for several hours “in order to make peace with what happened,” according to a zoo statement.

The zoo says Bana was a first-time mother. The baby’s father is Kwan, a 22-year-old silverback gorilla.

The baby was the first Western lowland gorilla born at the zoo since 2005.

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