Tornado siren activated accidentally in DuPage County for second time this week

A tornado siren was unintentionally activated for the second time this week in DuPage County. 

The DuPage Public Safety Communications said the siren was "not part of a planned test." Officials said the incident is under investigation. 

Officials in Villa Park, Wheaton, and Addison warned residents of the accidental activation just before 10 a.m.

Early Tuesday morning, DuPage County residents were woken up by tornado sirens. The sirens were accidentally activated by a DU-COMM staff member around 3 a.m. during a planned system test.

The test was supposed to check the technology without the sirens going out.

DU-Comm released a statement issuing an apology, saying in part: 

"As soon as the error was realized, DU-COMM staff deactivated the sirens. DU-COMM recognizes and appreciates the trust its member agencies and the public place in us, and we regret that our error caused unnecessary interruption or confusion. We sincerely apologize." 

The agency normally tests the sirens on the first Tuesday of the month at 10 a.m.

How do outdoor tornado sirens work?

Meteorologist David Yeomans says when it comes to the outdoor sirens across the Chicagoland area, the National Weather Service first issues warnings. Then it's up to each city and municipality to decide what to do with the information, including whether or not to activate warnings.

"There is technology for full automation when a warning is issued for your area that can trigger an alert, but it's really city and municipality-dependent," he said.

Yeomans says that some sirens still involve manual activation. 

He adds that if sirens are heard, out of caution, go indoors, seek additional information and have multiple ways to receive warnings.