RALEIGH (AP) — North Carolina police are asking the FBI to analyze a noise that caused mass panic at a Raleigh mall last weekend.

The Raleigh Police Department said in a news release Thursday that it hasn’t found any indication the noise was a gunshot. But it also hasn’t been able to rule out the possibility.

A recording of the noise from Saturday has been sent to an FBI lab for analysis. Investigators have interviewed people who called 911 to report seeing someone with a gun and ruled out that those sightings were related to the noise.

The reports prompted a massive police response as panicked shoppers ran for the doors or hid in stores until authorities got the situation under control.