The Cincinnati zoo says its two curious polar bears wandered into a behind-the-scenes service hallway through an open den door but never left a secondary containment area.

The zoo says the 17-year-old female, named Berit, and the 26-year-old male, named Little One, entered an inappropriate area Wednesday but remained contained and were never loose or a threat to the public.

A statement from zoo director Thane Maynard says staff followed protocols and safely returned the bears to their main holding area within two hours.

Visitors were moved inside as a precaution but were free to leave the zoo.

No injuries were reported, and the bears weren't hurt.

The zoo said the bears were resting in their den later Wednesday and could be back on exhibit as soon as Friday.