By Wyatt Buchanon
The San Francisco Chronicle
Related: Shots fired: ShotSpotter gunfire detection system provides leg up on 911
SAN FRANCISCO — Police officers have responded to more shootings in two violent San Francisco neighborhoods after the installation of sophisticated sound sensors that detect gunfire, according to a city analysis released Monday.
The analysis by the Mayor’s Office of Criminal Justice found that the sensors recorded 65 percent more instances of gunfire in portions of the Bayview and Western Addition neighborhoods in March and April than were reported by people.
“The goal of the system is simply to identify on a more accurate level gunfire in the city,” said Mikail Ali, a senior adviser in the criminal justice office. He said police respond to every report from the sensors.
In the Bayview, the sensors, which are manufactured by Mountain View-based ShotSpotter Inc., recorded 41 incidents of gunfire in March and April; police received calls alerting them to just 10 of those incidents.
Sensors in the Western Addition, which began operating in April, recorded 14 instances of gunfire; people in the area reported nine.
But while police are alerted to more incidents of gunfire, officers have made just one arrest and seized two firearms as a result of the sensors. In Oakland, where officials have installed similar sensors, the result has been two arrests and two firearm seizures in a year and a half, according to a report from that city’s Police Department.
San Francisco spent $400,000 for the sensors, which cover about 1 square mile in each neighborhood. Ali said it is too soon to know if their presence is a deterrent to such crimes.
Many of the recorded gunshots that prompted no calls from residents occurred late at night and in the wee hours of the morning, when many residents were likely to be sleeping.
Still, Ali noted the sensors alert police to gunshots an average of 2 minutes and 39 seconds faster than citizen reports and give precise locations of incidents, which he said has aided in the collection of evidence in three homicides.
Also, the few minutes of difference between when the ShotSpotter alerts police to a shooting and when citizens call could be critical for someone seriously injured by a bullet.
“I think that is significant and worth the cost, definitely,” Ali said.
Supervisor Ross Mirkarimi, who chairs a Board of Supervisors committee that was presented with the report and who has pushed the city to install the sensors, said they are worth the cost.
“Some communities have become numb to the fact that they have to live with gunfire every day, and it’s unreported. That’s just unacceptable,” Mirkarimi said.
Copyright 2008 The San Francisco Chronicle