Rebecca Gonzales, 27, was detained by Phoenix police on Friday and charged with aggravated assault

An Arizona mother has been arrested after she allegedly attacked her seven-year-old son 'for being a bad lookout for his shoplifting grandma'.

Rebecca Gonzales, 27, was detained by Phoenix police on Friday and charged with aggravated assault.

Court documents indicate that police responded to a suspected child abuse call at a Walmart located near 75th Avenue and Lower Buckeye Road on Friday night, KNXV reports.

There, they learned that Gonzales had come to the store to pick up her seven-year-old son, who was acting as a lookout for his grandmother while she shoplifted.

Officers allegedly saw the mother slap and punch her child in the face while they were in the parking lot.

Police responded to a possible abuse call at the Walmart located near 75th Avenue and Lower Buckeye Road (file photo above) and saw the mother allegedly hit her child in the face

And when they saw him up close, authorities discovered that the boy's mouth was bleeding.

Police say that the child told them he was hit because 'he didn't watch out for his grandma good enough'.

The grandmother's identity has not been released and it is unknown if she was caught shoplifting.

The status of the child is currently unknown.