All around New York City, cellphones blared on Monday morning with the dissonant, but familiar, tone of an emergency alert. But this time, the alert â typically used for weather-related advisories or abducted children â was different.
For what is believed to be the first time, the nationâs Wireless Emergency Alerts system was deployed as an electronic wanted poster, identifying a 28-year-old man wanted in connection with the bombings in Manhattan and New Jersey.
Suddenly, from commuter trains to the sidewalks of Manhattan, millions were enlisted in the manhunt.
The message, probably received by millions, nearly at once, was simple: âWANTED: Ahmad Khan Rahami, 28-yr-old male. See media for pic. Call 9-1-1 if seen.â
It roughly coincided with an appearance by Mayor Bill de Blasio at 7:30 a.m. on CNN, where he announced the name of the suspect and shared a photograph released by the Federal Bureau of Investigation. The authorities simultaneously spread the image on Twitter, hoping to ensure that those receiving the alert around 8 a.m. and after on their phones would have no trouble finding the image of Mr. Rahami.
The messages are targeted to a cellphoneâs location, so the alert on Monday was received by those in New York City, but not those in all parts of the state. A spokesman for the State Police said the decision to release the message came from the authorities in New York City; a spokesman for Mr. de Blasio said it was âa firstâ for such a purpose.
There are three broad types of alerts in the national system: emergency alerts for storms and other threats to public safety; so-called Amber Alerts, which seek to enlist the public in a search for an abducted child; and those issued by the president. Cellphone users can opt to block all but the presidential alerts.
The emergency alerts can be sent to the national system by federal, state or local authorities who have been authorized to do so and can include shelter-in-place instructions or evacuation orders precipitated by âsevere weather, a terrorist threat or a chemical spill,â according to the Federal Communications Commission.
In New York City, the alerts have been used eight times since 2012: three times during Hurricane Sandy, once to alert a travel ban during a 2015 winter storm and twice during the Chelsea bombing, according to city officials.
The first warning, on Saturday night, was directed at people in the Chelsea area, warning them to stay away from windows as the police cleared an unexploded device from 27th Street. The second went across the city to assist in the search for Mr. Rahami.
By late morning, law enforcement officials said Mr. Rahami had been captured.