Police officials on Wednesday unveiled preliminary results of the NYPD's new gunfire detection program. 

ShotSpotter was installed at 17 precincts last month.

The system uses microphones to pinpoint the precise location of gunfire. 

In one case, top NYPD brass say the technology detected a shooting in Brownsville where 24 rounds were recovered. They say 911 was never called and that police were only alerted because of ShotSpotter. 

In fact, they say in the 55 incidents of gunfire the technology recorded, 911 was called just 12 times.

"The good news going forward is that we’ll have a much more accurate picture of gun violence in the city," Bratton said. "We'll have a lot more evidence to work with as we retrieve the casings from these weapons. I think we'll end up making more apprehensions because our officers will be on the scene much more quickly."

Meanwhile, Bratton said major crime is down 10 percent through the first three months of the year compared to 2014, though murders and shootings are both up.