CHICAGO (AFP).— A small pre-dawn earthquake has hit northern Illinois, startling sleepy-eyed residents as far away as Iowa and Indiana, but no damage or injuries were immediately reported.

The U.S. Geological Survey says the 3.8-magnitude earthquake hit about 50 miles northwest of Chicago at 4 a.m. Wednesday. The USGS initially reported the magnitude as 4.3 but later downgraded it.

USGS geophysicist Amy Vaughan says such quakes are rare in northern Illinois. She says the agency received reports from Wisconsin, Iowa and Indiana about feeling the ground shake.

Sheriff's dispatchers near the epicenter in Kane County say they've been flooded with calls from startled residents. But spokesman Lt. Pat Gengler says no injuries or damage have been reported.

Residents reported being tossed out of bed and finding books and tools scattered across the floor.