TAMPA, Fla. (AP) — Seven African penguins have died at The Florida Aquarium , officials announced Thursday.

Initial necropsy results were inconclusive, but the Tampa facility’s veterinary team is conducting further medical tests and evaluations to determine a possible cause, according to a news release. The Florida Aquarium’s remaining penguins are receiving around-the-clock observation and care, officials said.

“It’s never easy to communicate the loss of a species ambassador, especially one as iconic as our African penguins,” spokeswoman Dale Wolbrink said in the news release. “The Florida Aquarium will leave no stone unturned in our efforts to understand this tragic course of events. Unfortunately, we may never know the cause of death.”

The African penguin colony has lived at The Florida Aquarium since 2006.