If you hear sirens in Aurora today, don’t be alarmed.

It’s not a tornado warning.

Or some other major emergency.

The city is testing its emergency outdoor warning sirens at 11:30 a.m. Emergency officials said the test will include more than 50 sirens throughout the city and will last for three minutes. 

Officials said the city conducts audible tests of its sirens twice a year to ensure they’re working in case of a real citywide emergency. The next one is slated for November.

During a real emergency, the sirens mean people should immediately take shelter and seek more information from local news and official government sources.