By John Dodge

CHICAGO (CBS) — In the early hours of Friday morning, thousands of Chicagoans were awoken to a startling, loud sound of an emergency alert coming from their phones.

It was not a text alert or a push message, but a Wireless Emergency Alert from the National Weather Service.

This one was for a Flash Flood Warning.

And for families with multiple phones, the sound became an alarm-clock-like symphony, coming at slightly different intervals over the course of about five minutes.

Older phones are not capable of receiving the alerts but the service has been active since the middle of 2012.

Some people I spoke to on Friday afternoon were annoyed that they received such an alert for a weather situation that would be considered somewhat dangerous but isolated, as opposed to a large severe storm with tornadoes.

In one case, a person said he got the alert and it wasn’t raining at the time, nor was there a body of water nearby.

A National Weather Service spokesman said the alerts are automated and are sent to any phone that is within range of cell towers and enabled to receive them.

He added that there is no consideration for the time of day. Phone users can turn them off. (More about that later.)

The Federal Emergency Management Administration and the Federal Communications Commission also participate in the service, meaning other alerts from the federal government are possible, too.

Those include: extreme weather warnings; local emergencies requiring evacuation or immediate action; AMBER Alerts and Presidential Alerts during a national emergency.

The NWS has placed seven alerts on its list, ranking five of them as extreme and two severe.

The extreme alerts are: Tsunami warning; tornado warning; hurricane warning; typhoon warning; extreme wind warning.

The severe alerts are: Flash flood warning and dust storm warning.

For us in the Midwest, only three of those would likely apply (tornado, wind and flash flood. Dust storm? Not likely. Tsunami, hurricane and typhoons? No)

As it turns out, according the NWS, phone customers can elect to block the warnings, with the exception of presidential alerts.

However, the procedures depend on your phone and possibly your carrier. You can start by clicking on this link and then click on the link to your carrier. You may have to do a bit of digging to find what you need.

For an iPhone 5s and 5, I selected Settings > Notification Center.

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Then I scrolled to the bottom and turned off both AMBER and Government Alerts. There was not an option, as far as I could tell, to customize which Government Alerts I wanted to block. For example, I would like to get a Tornado Warning alert, no matter the time of day.

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