It was a strange way to start the day. My work phone screamed out a noise that sounded like an air raid siren, flashing a message saying “WANTED.” Seconds later, my personal cell phone howled with the same message.
The alerts, received by millions of others in and near New York City, announced the search for bombing suspect Ahmad Rahami, who is wanted in association with a bomb blast in Manhattan on Saturday night. The alerts also represented something else: the first digital manhunt of this scale to take place in the New York City.
While law enforcement has long used digital billboards, along with radio and TV stations, to alert the public about a suspect, this is the first time the modern equivalent of a “wanted” posted has appeared in everyone’s pocket. Here’s a shot from Twitter displaying what the alert looked like:
As you can see, one strange feature about the alert is that it doesn’t actually include a picture of Rahami, but instead instructs the recipient to “See media for pic.”
It’s not immediately clear why the phone carriers didn’t transmit a picture with the alert. I’ve reached out to AT&T (T) and Verizon (VZ) to find out if the decision not to send an image is related to technology, or is a policy decision. (I’ll update when I hear back.)
Get Data Sheet, Fortune’s technology newsletter
The wanted message is the first of its kind, but cell phone carriers have issued similar alerts (complete with the siren noise) on a number of previous occasions. The most common of these is for “Amber Alerts,” which advise people about missing or abducted children. The phone companies have also used them to advise customers about severe weather situations.
The alerts on Monday represent an unprecedented form of crowd-sourced law enforcement that could prove extremely effective, but may also raise questions about privacy and civil liberties if they become used on a regular basis.
As of 10:45 a.m. ET on Monday, Rahami had yet to be apprehended. Update: Rahami has been caught after a shoot-out with police in New Jersey.