ST. LOUIS (KMOV.com) -- Two harbor seals headed to the Saint Louis Zoo from a theme park in Canada died in transit on Friday.
Officials said the animals were part of a shipment of four adult harbor seals coming to join 11 sea lions in the zoo's new Sea Lion Sound exhibit opening at the end of June.
According to a release from the zoo, the two seals were checked frequently during the journey and appeared healthy. At a check point, however, one seal was not responsive, and another showed signs of distress.
A veterinarian from the nearby Fort Wayne Children's Zoo later confirmed one seal was dead, and worked to save the second animal. Despite their efforts, the second seal died.
The release said a third seal showed similar symptoms and was left at the Indianapolis Zoo to undergo treatment.
The remaining animal arrived in St. Louis on Saturday afternoon and appeared to be healthy.
Zoo officials said the seals' cause of death will not be known until all tests are complete, a process that could take several weeks.