PITTSBURGH (KDKA) – Police are urging anyone who hears a strange recording in the South Side to call 911 immediately.

Pittsburgh Police say they’ve received multiple recent reports from people on the South Side who say they hear what sounds like a recording of a baby crying or a child asking for help.

On four separate occasions, officers have responded. However, they say in each case they were unable to hear the sound or figure out where it was coming from.

Anyone who hears anything suspicious is asked to call 911 and stay inside.

Two college sorority sisters who’ve lived on the South Side say they feel safe living here.

But not anymore.

“We’ve been staying together and not letting anyone be alone,” one sorority sister said.

This week, they say they heard what seemed like recordings of babies crying and someone shouting for help right outside their door.

“I just think they know a lot of young college girls live in South Side, and we just have really kind hearts. And obviously, if anything was happening, we would want to help as much as we can.”

Police are investigating.