In what circumstances will police respond to reports of a shooting?

In People v. Blacksher (2011) 52 Cal.4th 769 (Blacksher), the declarant spoke to an officer at her house, where her daughter and grandson had been fatally shot. The officer arrived within four minutes of the dispatch. The declarant said the gunman was her son. The responding officer spoke with the declarant for approximately 15 minutes. The officer asked questions about the shooting, including questions related to the defendant's current location. The officer learned the defendant was not at the house so the officers presumed the defendant was an armed shooter. The declarant was visibly upset, and the interview occurred in the front yard of her house with a neighbor present, under chaotic conditions. (Id. at pp. 816-817.)