Officials at Zoo Knoxville have been investigating the recent deaths of 33 reptiles.
Media outlets reported nearly all of the reptiles were snakes that were found dead in the zoo's reptile area last week. Other surviving animals were removed and given oxygen.
Zoo Knoxville President and CEO Lisa New called the deaths a "devastating and catastrophic loss."
The building where the reptiles were found has been taken out of use while the deaths are being investigated.
Zoo director of animal collections Phil Colclough said among tests being conducted are for harmful gases in the building and for mechanical errors on thermostats.
