Millions of phones began blaring across the city after a public-warning specialist in the city’s Office of Emergency Management pressed the button upon NYPD’s request. 

Out of the chain of command? Mayor Bill de Blasio.

In a fast-moving scenario like Monday’s, “you spend a lot of time using every potential option for communicating to make sure the public is aware,” said J. Peter Donald, NYPD’s assistant commissioner for public information.

Though Donald couldn’t specify what source led a New Jersey resident to identify Ahmad Khan Rahami, the man now in custody for blasts in Chelsea and New Jersey last weekend, the NYPD credits some combination of the information surge pushed out between 7 and 8 Monday morning. That info went to news outlets and social media. 

Notably, it also went to smartphones citywide. It was a blaring alert that either woke you up or erupted wherever you were: a communal experience with countless others in the subway or on the street. 

It’s a new and surprising capability that quickly brought calls of support for the new tech, as well as criticism that it raised tensions and didn't provide useful information in the hours after it was sent.

A tool for reaching almost every cell phone

Both NYPD and the city’s Office of Emergency Management say that when you have a bomber situation, you want to make the public aware quickly and not wait for too many confirmations.

Ben Krakauer, emergency manager at OEM, says his office’s threshold for using the national system in NYC is “very, very high.” Not a house fire or flooding, for example, but rather threats to safety and incidents in which OEM wants the public to take a certain action.

The city has had the capacity to send the alerts, called Wireless Emergency Alerts, since 2012. Since then, it has only done so eight times: three times during Superstorm Sandy, once for a blizzard that was, and once for one that wasn’t. 

And three times last weekend, related to the Chelsea explosion.

The first two were targeted alerts urging caution, sent to a "polygon" drawn around Chelsea. By default, the technology targets a county, though service providers can voluntarily allow OEM to communicate granularly over smaller areas using a single cell phone tower. 

The 21st century wanted poster sent Monday morning, however, went to the whole city. The technology is still imperfect — Krakauer said OEM received anecdotal reports that some people in New Jersey, for example, received the message. (There is no data on exact number of phones reached because the technology is designed to be a one-way operator, like radio.)

There are other issues with the system. Right now, it can’t support more than 90 characters, a multilingual message or--crucial if you’re trying to send a wanted poster — a picture, according to Krakauer.

Krakauer says the FCC could move to add those capabilities in the coming months. He’d also like more targeting to use the system as granularly as possible — down to the building level, even, to warn about extreme weather or incidents of local violence, while being mindful of warning fatigue. 

If those improvements occur, the alerts may well become a more routine part of life.

Do we know enough about the process for sending alerts?

Precise targeting for weather or other emergencies might not create much of a stir, but the warning poster was different. 

Lacking a picture or any details about the suspect other than an Arab name, some New Yorkers wondered if whether the blaring disruption was not a safety option but an invitation for stereotyping.

Sarab Al-Jijakli, a community organizer and advertising executive, for example, woke to the alert and was startled. Partially, because his own middle name is Ahmad. And he worried that a message like this would encourage people to see anyone who looks like an Ahmad, a Khan, or a Rahami as a suspect.

“It creates a hysteria around people,” said Al-Jijakli, 40, “rather than the calm and focus we need.

He later took to Twitter to join many others surprised and somewhat confused about the mass capability that the city had utilized.

Yesterday, local officials lauded the public’s see-something-say-something vigilance in this case. It may have been the difference law enforcement needed, and wide alerts could be useful in the future. 

But it’s a far leap from posters and news blurbs to the devices that sit in our pockets and lie next to our beds.

That proximity and the technology's newness make this a trickier add — another adjustment in a world of terror threats and widespread technological reach.