CINCINNATI -- Visitors and staff were evacuated from the Cincinnati Zoo due to a threat Thursday afternoon. Police gave the all-clear less than two hours later.

A threat was made over the phone, Lt. Steve Saunders said. There was a report of a suspicious "device."

About 50 visitors and 75 zoo staffers were evacuated. K-9 units swept the zoo and found no devices or other threats, Saunders said.

The zoo closed at 5 p.m. but will resume normal operations Friday, the zoo said in a news release.

Police were reviewing the source of the phone call.

The zoo released the following statement:

"The Cincinnati Zoo & Botanical Garden safely evacuated staff and guests today around 3:30 p.m. as a precaution after an unspecified threat was called into Cincinnati Police. The Zoo takes all threats seriously. We will continue to work with Cincinnati Police to ensure the Zoo remains a safe environment."

Watch the full press conference below:

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