Downers Grove officials said DuComm was testing the system and the tornado siren was set off without any severe weather to be concerned about.
A new automated system was put in place on May 1, 2025.
DuPage Public Safety Communications said in a statement that staff was conducting a planned test of the siren systems.
"During the test, the staff member accidentally activated the sirens. As soon as the error was realized, DU-COMM staff deactivated the sirens," the statement said.
"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."