A Wendy’s worker was shot through a drive-thru window in Illinois following an argument with a customer, police say.

The shooting happened around 1 a.m. Thursday, April 4, at a Wendy’s in south Chicago, according to the Chicago Police Department.

Police said a 20-year-old Wendy’s employee was working the drive-thru at the restaurant when a male customer began arguing with her. Then, the man fired shots through the window.

Footage from WGN shows at least one bullet went through the window, shattering the glass. At least one shell casing was found on the ground, the station reported.

The worker was struck in the arm and was taken to a hospital in “fair condition,” police said.

The customer, who has not been identified, fled after the shooting, police said. No arrests have been announced as of late Thursday morning.

Police said the shooting remains under investigation.

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