A 20-year-old Michigan mother has been charged with assault after police say she punched a grocery store clerk in front of her 1-year-old daughter.

Surveillance video caught the incident unfolding Monday at a Kroger store in St. Clair Shores. Police say Shelby Parham was in the self-checkout area prior to walking up to a 49-year-old clerk and hitting her in the face. The woman was knocked flat on the ground, rendered unconscious and suffered a head injury. 

"It's obviously very clear-cut. There's no questions as to who's at fault here," St. Clair Shores Police Detective Gordon Carrier told FOX 2 Detroit. 

Investigators say some words were exchanged by Parham and the clerk after her electronic benefit transfer, also known as Bridge card, did not have enough money to cover what she rang up. Parham reportedly asked for help to deduct some of the items from the register, but the clerk could not help her at that moment. 

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"The employee walked away from her. The defendant was upset and followed her and struck her in the face," Carrier said. 

When the incident occurred, Parham's 1-year-old daughter was sitting in her shopping cart.

Police arrived at the store within minutes and took Parham into custody. 

She was given a $1,000 bond and is no longer in custody, but she could face up to one year in prison if convicted of the misdemeanor.

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The unidentified store clerk sustained a black eye, is suffering from headaches and is taking time off from work to recover at home. 

Kroger did not immediately respond to a request for comment.