An orangutan bit a zookeeper’s hand through a mesh barrier, causing a serious injury, a Washington zoo said. The incident happened Saturday at the Woodland Park Zoo in Seattle, the zoo wrote in a Facebook post. The keeper was doing a “routine training session” with the animal when it bit her, the zoo said. The zoo said the worker was taken to a hospital to get treatment. No one else was injured during the incident, the zoo said. A veterinarian performed an exam on the orangutan and said it was “safe, unharmed and behaving appropriately.”

The zoo said there is always “protected contact” like mesh or a fence anytime a zoo worker encounters an orangutan. It’s also common for keepers to have training sessions with these animals every day. “Training encourages the animals to voluntarily participate in their own care by helping them become more comfortable with daily husbandry and medical procedures,” the zoo’s senior director of animal care Dr. Luis Neves said in the Facebook post. These sessions also help the animals bond with the workers, build trust and add enrichment to their lives, Neves said.

The zoo is investigating the incident and evaluating protective barriers at enclosures. There are four adult orangutans at the zoo and the habitat is open to viewing for guests.