(KMOV)-- If you depend solely on tornado sirens to warn you of imminent danger you are taking a big risk. Emergency management officials in St. Louis County say even when a storm hits late at night, sirens are not guaranteed to save you.
Mark Diedrich with the St. Louis County Emergency Management says officials are investigating nearly 100 complaints. He calls it a mistake to assume you can hear a siren inside your home at night.
Officials admit 29 of their 200 sirens either don't work properly or don't work at all. A siren at Olive and Stablestone sounds a warning, but can no longer rotate to warn residents on all sides. As a result, those living a short distance behind it may not hear it.
The county is spending millions to install 180 new sirens. Many are already up, but the system won't be operational before August. Even then, the system comes with it's own warning.
"It's an outdoor warning system. It's not designed to hear in your home," says Mark Diedrich.
Click here for the full list of broken tornado sirens.