CHICAGO — Just after 3 a.m. on May 4, a police officer received an alert that gunshots had been fired near an alley in a neighborhood known as the Back of the Yards.

The alert came from a hidden street sensor called a ShotSpotter, and the officer was able to pull up a map of nearby police cameras and review the video. Without leaving a room the size of a walk-in closet, he watched a man fire seven times, striking another man, who turned out to be a federal agent, in the face.

Switching from one high-definition camera to the next, the officer tracked the gunman as he fled. Unlike the grainy security videos of old, the picture quality from the cameras, which are equipped with night vision technology, was so pristine that the officer was able to watch the man wipe sweat off his face.

The tiny rooms have a large-sounding name, Strategic Decision Support Centers, and provide a peek into what could be the future of urban American policing — if they do not run afoul of American notions of privacy. They can deliver the license plate of every passing vehicle, a photo of every area resident with an arrest record, gang boundaries, 911 reports and more, right to a patrol officer’s cellphone.