SAN DIEGO—One of the problems faced by the law-enforcement community is that when a firearm is discharged, many times the incident is never reported. That reality led the city of San Francisco to deploy a gunshot-location system developed by Mountain View, Calif.-based Shotspotter a year and a half ago in two districts prone to such incidents.

That decision has worked out so well that the city will deploy the system in a third district next month, said Mikail Ali, senior advisor for public safety in the Mayor’s Office of Criminal Justice, who spoke yesterday during an educational session at the International Association of Chiefs of Police annual conference.

“There is a tremendous amount of gunfire that isn’t reported. … The general rule is that if you receive 100 calls reporting gunfire, there really have been 200,” Ali said.

There are several reasons for this. Fear is chief among them, according to Greg Rowland, senior vice president of Shotspotter. “A lot of times there are no witnesses, because they’re afraid of retribution, or they simply ran like hell as soon as the shots were fired,” Rowland said.

Apathy is another reason, according to Ali. “In some areas, there is so much gunfire that people become numb to it,” he said.

Still another reason is that gunshots often sound similar to other sounds. Rowland described an incident where multiple firecrackers were exploded just prior to a gunshot. “No one called it in because they thought it was another firecracker,” he said.

Ali agreed. “Even a trained law-enforcement professional can’t always identify gunfire from other sounds,” he said.

The city deployed the Shotspotter system in Bay View—where there is “lots of crime and gang activity,” Ali said—in a footprint that covers 1.3 square miles, and in the Northern district, covering 1 square mile. The latter district, which includes the Fillmore and Nob Hill sections of the city, is affluent and “at the opposite end of the demographic spectrum,” from Bay View, according to Ali. Nevertheless, the Northern district was chosen based on the amount of gunfire and homicides that occur in it.

Ideally, the city would deploy gunshot location systems across 15 square miles, based on homicide statistics, Ali said. The city covers 49 square miles. “Eighty percent of homicides are committed with firearms,” he said.

The impact of the Shotspotter system in San Francisco has been noteworthy. In Bay View, the system has detected 166 gunshot incidents; of these, only 21 were reported. Meanwhile, in the Northern district, Shotspotter detected 89 gunshots; of these, just 34 were reported.

The ability to immediately identify gunshots cuts response times, resulting in more arrests and increasing the potential for saving lives, Ali said.

According to Rowland, there’s no potential about it. “When no one calls 911, people bleed to death,” he said.

The system not only identifies that a gun has been fired, but it also can determine the type of weapon(s) fired and the sequence of the shots. This improves situational awareness, which in turn enhances a dispatcher’s ability to deploy the appropriate resources to the incident. It also helps to keep inexperienced officers from “rushing into a situation they’re not ready for,” Ali said. The ability to determine the sequence of the shots that were fired also is helpful to investigators trying to determine whether an incident was a homicide or self defense.

Finally, gunshot location systems can be instrumental in protecting officers from wrongful accusations. Rowland told of an incident involving two Washington, D.C. police officers who were accused of wrongfully shooting a teenager. According to Rowland, “hostile” witnesses insisted the victim was unarmed and had never been in any trouble.

“These [officers] were in a lot of trouble,” he said.

However, the Shotspotter system in place in the city not only established that the youth was armed, but he had fired the first shot, which exonerated the officers, Rowland said.