A rare moderate earthquake disturbed northern Illinois Wednesday morning, waking up residents in the Chicago area.
The 4.3 magnitude quake, centered 48 miles west of Chicago near the city of Sycamore, hit at 4 a.m. local time at a depth of about 3 miles, the USGS reported.
Geophysicist Amy Vaughn told the Chicago Sun Times the earthquake was "very widely felt" and the USGS phone lines were flooded with calls from residents asking about the shaking.
"It's mostly people who said 'we woke up and we thought we were going crazy,'" Vaughn said. "Mostly it’s rattling people awake."
Dispatchers have been flooded with calls from startled residents, though no injuries or damage have been reported.
Several residential and business alarms were triggered, but deputies haven't been called for assistance.
Residents reported being shaken out of bed and finding books and tools scattered across the floor after falling from shelves.
Early reports suggest the quake was felt across three states: Illinois, Indiana and Wisconsin.
FoxNews has contributed to the report.