According to the report:
An officer was traveling south on U.S. 27 near Primrose Road at about 12:45 a.m. when he heard two loud pops and saw that the window was broken.
After stopping and checking for the cause of the damage he observed two impact marks on the frame around the window that appeared to be from a rock.
A small fragment of a rock was found in the patrol car’s rear floor, and the rest was discovered in the roadway.
Several officers responded to the scene in an attempt to locate a suspect for damaging city property, but they were unsuccessful. No other vehicles were on the roadway at the time of the incident.
The report did state that a slingshot was possibly used.