DENVER (CBS4) – The Denver Zoo was closed for more than an hour on Tuesday because of a security threat. Zoo officials first called it a credible security threat, but police and zoo officials later clarified said the threat has not been deemed credible.

Police blocking entrances to the Denver Zoo. (credit: CBS)

Police officials say a threat was called into the zoo, and they say the threat was of someone planning to crash a plane at the zoo.

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(credit: CBS)

They add they’ve been in contact with several airports, but it’s unclear what information they’ve gathered from those conversations.

Zoo visitors were evacuated from the property, but East 23rd Avenue and roads leading in and out of City Park are reopening.

(credit: CBS)

“We were getting minimal information, but it was something about a pilot flying around claiming that he was going to be crashing into or near the zoo, so they evacuated everyone and just kept pushing us further and further out,” said Karalee McMillan who was visiting the zoo with her daughters.

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Karalee McMillan (credit: CBS)

Bert Vescolani, the new president and CEO of Denver Zoo, says about 1,000 guests were evacuated.

The zoo updated to say they will be open during normal business hours on Wednesday.

Below is their statement on Tuesday evening:

Just after 3 p.m. this afternoon, we received a call from an unidentified individual threatening to fly an airplane into Denver Zoo. We immediately contacted Denver Police and other government agencies, initiated an evacuation of all guests and staff on the premises and moved animals to safety. Denver Police quickly responded to help secure the grounds and investigate the threat. Less than two hours later—around 4:45 p.m.—Denver Police determined that the threat was not credible and allowed Zoo patrons to return to their vehicles so they could leave the area. The investigation into the threat is ongoing.

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Our top priority is the safety and comfort of our guests, staff and animals. We take every threat very seriously and consistently review and practice our procedures to maintain the utmost safety standards. Denver Police has reopened 23rd Ave. and Denver Zoo will open tomorrow with normal hours (9 a.m. to 5 p.m.).