MEXICO CITY -- Police say residents of a Mexico City neighborhood called to report buffaloes standing in the street Monday, saying they didn't know what to do.

Two officers were sent to the scene and used a flashlight to herd the animals back to a pen from which they appeared to have escaped.

A man showed up at the pen saying he was in charge of the buffaloes and thanked the policemen for returning them.

Police say they will investigate whether the animals are being properly held there.

More than 20 million people live in the megalopolis that is Mexico City and its surrounding suburbs -- an urban home where buffalo aren't known to usually roam.