The attack happened early Sunday morning, when one of the pandas was able to get out of her enclosure and into an area where the animal keepers were working.
"One of the pandas pushed on a door that was not properly secured and was able to exit into the keeper area," said San Diego Zoo Spokesperson Christine Simmons. "One of the keepers was bit."
The zoo is not releasing the condition of the zookeeper or where the keeper was bitten. The panda, named Bai Yun, has been at the zoo since 1996 and has given birth to five pandas there.
It's the first time a panda has attacked anyone at the San Diego Zoo.