Across New York City, cellphones blared on Monday morning with the dissonant but familiar tone of an emergency alert, typically used for weather-related advisories or abducted children. But this was different.

For what is believed to be the first time, the nation’s Wireless Emergency Alerts system was deployed as an electronic wanted poster, identifying a 28-year-old man sought in connection with the bombings in Manhattan and New Jersey over the weekend.

Suddenly, from commuter trains to the sidewalks of the city, millions were enlisted in the manhunt.

The message was simple: “WANTED: Ahmad Khan Rahami, 28-yr-old male. See media for pic. Call 9-1-1 if seen.”

In an instant, the reach and ubiquity of law enforcement in an age of terrorism and digital technology became apparent.