CHICAGO (CBS) — Twice in a span of about nine hours on Monday, Illinois State Police responded to reports of shots fired on the Eisenhower Expressway, but there were no injuries.

Around 1:20 p.m., a witness saw two vehicles headed east and shooting at each other on I-290 near Kedzie Avenue, police said. No injuries were reported, but police did find a shell casing on the expressway.

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Later, at about 10:30 p.m., another report of shots fired came in from the inbound lanes near 17th Avenue in Maywood. Police shut down the Eisenhower for about four hours to investigate, and search the lanes for shell casings.

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“I stay right there at the corner house, and I heard a few shots, but I thought it was just shooting across the bridge or something like that. I heard a lot of ruckus, and I just came outside, and I just seen all the lights and stuff,” said Quincy Smith, who lives nearby.

Cameras captured a car that swerved off the road and ended up in a ditch when the shots were fired, but no one was injured.

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There have been at least six shootings on Chicago area expressways so far this year. In 2016, there were at least 48 such shootings.