CALGARY, Canada – The Calgary Zoo in Canada announced Thursday the deaths of seven Humboldt penguins in the Penguin Plunge exhibit.

The birds were in their back holding area, which is regularly used to house the penguins, the zoo said.

The zoo’s veterinary team completed necropsies on all the birds. The results determined the birds died as a result of drowning, the zoo said.

Get Breaking News Delivered to Your Inbox

“This is devastating news,” Jamie Dorgan, the director of animal care, said in a statement. “We have launched a full investigation so we can try to understand what happened and prevent further incidents like this from happening again.”

There were a total of 22 birds within the Humboldt colony. Three other species live in Penguin Plunge including kings, gentoos and rockhopper penguins.