If you hear a siren across the river, don’t be alarmed. The City of Detroit is doing its monthly outdoor warning siren system test at 1 p.m. The city has 56 sirens throughout the city and is tested the first Saturday of every month at 1 p.m. Sirens are designed to be heard outside, not inside, and are used in the event of severe weather, an emergency, or national disaster. Detroit says if you ever hear the sirens outside of the testing period, you should go inside to an interior, windowless room on the lowest level, and monitor local media for official instructions and the type of emergency.