Controversial crime-fighting tool ShotSpotter was debated Tuesday night at Sacramento City Hall. Police say it helps increase response times, but others say it's a waste of money.

After more than an hour of discussion and debate, the Sacramento City Council voted 8 to 1 to approve spending more than $2 million on ShotSpotter over the next five years, but they also want the police department to provide an annual review of the technology.  

When someone fires a gun in some Sacramento neighborhoods, police say about 80% of the time, nobody calls 911 to report the crime.

That's why, since 2015, Sacramento police have been using ShotSpotter, a network of outdoor acoustic sensors that can hear gunfire from up to three miles away and pinpoint its location.

The technology is now located in the north, south, and east parts of the city. Over a four-year period, Sacramento police say they have detected more than 4,100 shots fired. But opponents complain about the cost.

"I think it's a bad idea and a terrible waste of money at a time when we're about to enter our third year of projected budget deficits," civilian Keyan Bliss told CBS Sacramento outside city hall.

The city pays more than $500,000 a year to operate the system, and that doesn't include the officers needed to respond to the calls.

Councilmember Mai Vang was the only no vote.

"I believe we should be prioritizing and investing in resources that actually prevent violence," Vang said ahead of the vote.

Some people think the money would be better spent on crime prevention efforts.

"We could be investing in programs that actually practice proven techniques that intervene in gun violence to help reduce and stop the shooting from happening in the first place," Bliss said.

Supporters say the technology helps improve police response times and locate suspects and gunshot victims more quickly.

"When that activation comes back to us, officers within a minute are able to get a longitude and latitude and start driving there to identify any victims that need help, as well as any suspects who may still be in the area," Sacramento Police Captain Ethan Hanson said during Tuesday's meeting.