PHILADELPHIA (CBSDFW.COM/AP) — Four peacocks escaped from the Philadelphia Zoo and casually took a stroll on a nearby highway.

The birds were spotted walking on Interstate-76 around 8:30 p.m. Wednesday. State police arrived and shut down two lanes of traffic on the highway, causing backups for miles.

Police say they managed to get the birds off the highway, but they were unable to capture them.

Zoo officials say the peacocks have gone to roost for the night, and they will work with police to recapture the birds Thursday morning.

The zoo says the flock roams freely on its grounds, and it is cared for by veterinary staff. The zoo admitted, “The peacocks do sometimes venture past the Zoo’s gates and typically return home on their own.”

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)