Map: Location of Quake
Many downtown offices and apartment buildings were evacuated and people flooded into the street after the tremor shook the downtown area.
People who milled in the street talked about what the earthquake had just interrupted in their lives. One person said it felt like a big truck rumbling past.
From the sixth floor of her condo in downtown Arlington Heights, Ellen Hanrahan said she felt her building do "a back and forth sway for about eight seconds." She said her cat stopped eating "and hunkered down on the floor -- which is very strange for him."
Hanrahan noted that friends of hers in Rochester, NY and Pennsylvania have also reported feeling the quake.
In Des Plaines, Tracy Raetzman said she felt it from the second floor of her office at Wheels Direct.
"We all weren't quite sure what it was," she said.
In the Boston area, concern over the tremor prompted police to evacuate an eight-story medical office building, the Boston Globe reported.
Earlier this year, a 3.8 quake centered in a farm field near Hampshire, Illinois woke up residents all over the Midwest. And in April 2008, a 5.2 magnitude quake hit West Salem, about 270 miles south of Chicago.
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