TUCSON, Ariz. -- A 911 caller witnessing the mass shooting outside a grocery store in Tucson describes a frantic scene and says, "I do believe Gabby Giffords was hit."

In a tape of the call released Sunday by the Pima County Sheriff's Office, a person putting up a display for a pill bottling company was among the first to report the crime.

The caller says: "It's Giffords! There was a shooting at Safeway at Ina & Oracle where Gabrielle Giffords was. I do believe Gabby Giffords was hit. A guy had a semiautomatic pistol. He went in and just started firing and he ran."

The caller described the shooter as wearing a black hoodie, blue jeans and a black sweater.

The call was one of nearly 20 calls to 911 about the shooting.

WARNING: DISTURBING AUDIO