If you hear gunfire on Wednesday night in Montbello, it’s likely the police.

They’ll be testing ShotSpotter, a network of acoustic sensors that can determine when and where guns are fired.

To test the system, professionals will fire guns into “bullet traps,” which is obviously safer than the alternative. It’ll happen from 8 p.m. to midnight on Wednesday.

“No bullets will be fired into the air or ground, and there is no danger to the public,” according to the police. It’s happening at night because most shots are fired at night, and the system has to be tuned to the sound qualities of the night.

Police don’t disclose where ShotSpotter outposts are located, so I can’t say for certain whether this system is totally new to Montbello or not.

However, we do know that police started using the sensors early in 2015, and that they’ll triple the size of the coverage area this year. Once the system is in place, it automatically notifies 911 responders of shots fired.

Denver police received two grants, worth $525,000, for this year’s expansion. The department wants to expand coverage even more next year and is asking for another $165,000 in the 2017 budget.