We now know what caused an unexpected wake-up call in Crystal Lake Tuesday morning.
Tornado sirens went off in the suburb around 6:40 a.m. by accident.
Crystal Lake Police and Fire said in a statement that a wire shorted while new radio consoles were being installed, triggering the emergency alarms.
"This short simulated an activation on the system setting the sirens off for the community," the department said. "Once made aware of the situation, the vendor immediately reversed the issue silencing the system."
The city said it is working with the vendor to make sure false activations don't happen again during their work.
"The vendor, SEECOM [Southeast Emergency Communications], and the City apologize for any inconvenience to our citizens this may have caused," city reps said in a statement.