It happened Saturday at a McDonald's in Des Moines.
Police said the fight started because the customer wasn't getting her McChicken sandwiches quickly enough.
Another customer captured it on her phone while she was there buying ice cream with her children.
"Automatically, just because of how irate she was, I took out my camera and recorded her. Just to see how far it would go in case, and it just escalated really quickly," witness Amanda Gravely told KCCI.
In the video, the female customer is heard yelling profanities toward the manager. She was also with two men, one of whom can be heard screaming, "Give me my (expletive). Scared, aren't you?"
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The employee gave the woman her food, but the customer threw the McChicken in her face.
The woman got on the counter and started knocking over bottles.
The manager then dragged the woman by her hair.
The two men who were with the women try to hold other employees back as the customer pulled the manager's hair and kneed her in the chest.
The customer and two men left the restaurant before police arrived.
Police are still working to identify the customer in the video.
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