Some civil defense sirens used Roots blowers to pump air to the rotor (chopper).

In some areas in the United States, civil defense sirens may sound in the late morning and early afternoon on a regular basis.

Early Saturday morning, sometime around three, the civil defense siren atop the courthouse began yowling.

It wasn't very long before the civil defense siren began wailing.

The civil defense siren wailed for almost fifteen minutes, a sound so spine-chilling it even silenced the dogs.

Since then, many counties have reinstalled civil defense sirens removed after the Cold War.

This was also the first time in Minnesota state history where civil defense sirens were used for severe weather purposes.

In many Midwest towns, like Joliet, a tornado warning will also set off public defense sirens.

Nonetheless, the city's public transportation continued, stopping only when the local civil defense siren went off.

"This time of year, the biggest news would probably be that tornado season is coming and, oh God, did the civil defense sirens get updated?"