NEW YORK (CBSNewYork) — The Reptile House at the Bronx Zoo was closed Saturday after an adolescent Egyptian cobra went missing from an off-exhibit enclosure.

Zoo staff said they immediately closed and secured the building after learning the snake was missing. Egyptian cobras are poisonous.

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Officials at the zoo said they were confident that the snake, about 20-inches long, was confined to an isolated, non-public area of the building. Snakes typically seek closed-in spaces, and are uncomfortable in open areas.

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“We are informing the public out of an abundance of caution, and will continue to take whatever steps necessary to ensure public safety,” the zoo said in a statement.

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The Reptile House will be closed indefinitely, zoo staff said.