Denver sent out a blaring emergency text message alert at 5 p.m. Tuesday, marking the moment the city’s “stay-at-home” order went into effect, but some people never received it.

“Mine didn’t come. Maybe I’m too close to Aurora,” one Twitter user wrote.

Another Denver resident tweeted: “My partner received it. She is on TMobile. I am on Sprint. Nothing.”

Denver’s Office of Emergency Management said there could be numerous reasons why not everyone received the text, however there is no way to know how many people may have missed it.

“For this system, we administer it, but we do not control it,” spokeswoman Loa Esquilin told Colorado Politics.

The emergency text messaging system, which sends digital alerts in English and Spanish, is controlled by the Federal Emergency Management Agency and the Federal Communications Commission.

Esquilin said that factors such as cell phone carriers, personal phone settings, poor cell phone signals and cell phone models could all play a role into whether the alert was received.

Each September, Denver conducts an annual test of its emergency text alert system and sends that data back to the FCC so that it can make improvements where needed.

The emergency messaging system is free of cost to both the city and text recipients, Esquilin said.

Denver’s stay-at-home order will stay in effect until April 10, although Mayor Michael Hancock said it could be extended if needed.