A longtime resident of the Calgary Zoo’s river otter enclosure has passed away following an incident officials are calling ‘unfortunate and very upsetting’.

On Thursday morning, a zookeeper noticed Logan, a 12-year-old male otter, was struggling in the pool. The keeper entered the enclosure to assist Logan but the animal did not survive the ordeal.

“This is a very tragic incident that we are all trying to cope with,” said Colleen Baird, Calgary Zoo generator curator. “We appreciate the consideration while we continue to sort out the details of today’s event.”

The zoo’s three surviving river otters, 16-year-old Callebaut, 12-year-old Charlotte, and one-year-old Finnegan, remain on display at their home within the Cequel Lodge in the Canadian Wilds section.

Zoo officials have launched an investigation into the incident.