Cambridge Police report officers will fire guns between 8 and 9:30 p.m. in Area 4 and Inman Square to test the city's new system for detecting gunfire.

The city is installing a ShotSpotter Flex system, which uses sensitive sensors and software to help police "hear" gunfire. The tests are to help calibrate the sensors. Boston has had a similar system in place in high-crime areas for several years now.