That emergency alert message (and audible squawk) received by many Angelenos yesterday via their smartphones was just one big mistake.

While Monterey Park Fire Department officials blamed “testing” of the ” Integrated Public Alert & Warning System (IPAWS) through FEMA,” that's not really the whole story.

See also: Monterey Park Emergency iPhone Alert Scares The Heck Out of L.A.

Somebody screwed up. And it appears to have been a violation of FCC rules:

A source with knowledge of the situation says an honest mistake was made, but a mistake nonetheless, when a third-party vendor helping Monterey Park manage its alert system perhaps misunderstood instructions from the city and blasted the “this is only a test” message — live!

In other words, it was not supposed to reach your phone.

Test alerts are not supposed to go live, or use live code, the source says. In fact, live tests that rock our mobile phones are not supposed to happen at all — the FCC apparently forbids it.

For good reason: The messages shook up many Angelenos. The first went out shortly after 2:15 p.m. yesterday, but they apparently happened more than once afterward:

The Monterey Park Fire Department seemed to acknowledge the problem:

A Monterey Park fire official suggested to the Weekly that compliance with Federal Emergency Management Agency rules about testing the smartphone alert system triggered the mistakes.

And the fire department tweeted this similar stance:

But fire officials also apologized:

We reached out to the department several times to get a better explanation. But the folks who we were told were authorized to speak — a captain and a battalion chief — never returned our calls.

Send feedback and tips to the author. Follow Dennis Romero on Twitter at @dennisjromero. Follow LA Weekly News on Twitter at @laweeklynews.

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