The Cincinnati Zoo has been evacuated and police are investigating after a report of a suspicious package.

The zoo says staff and visitors were safely evacuated mid-afternoon Thursday after the threat was called in to police.

Cincinnati police say bomb sniffing dogs are sweeping the zoo. Lt. Steve Saunders says there's no sign so far of a package.

The zoo has been the target of critics on social media and elsewhere after a gorilla named Harambe was shot and killed by a special response team in May when a 3-year-old boy fell 15 feet into a moat inside the gorilla's enclosure.

The zoo reopened its gorilla exhibit in June with a higher, reinforced barrier.