A run to a neighborhood market spiraled into what investigators call an unthinkable act of cruelty when a mother, frustrated over a toy she couldn’t afford, bit down on her 4-year-old son’s ear and tore into her older boy, police said.

The violence, caught in detail on security cameras inside and outside Fatty’s Market in Hialeah, led to the arrest of 43-year-old Madelien Inurrieta-Martinez.

According to an arrest affidavit, the Nov. 4 episode began mundanely enough: Inurrieta-Martinez sat resting on stacked boxes of sodas near the aisles. But when her 4-year-old began pleading for a toy she didn’t have the money to buy, the situation turned explosive.

Police say Inurrieta-Martinez first lashed out at her 7-year-old son, grabbing the boy by his ears and hauling him across the frame before yanking him violently by his hair. Moments later, she turned her fury onto the toddler.“The defendant admitted that, while angry with the 4-year-old, she grabbed him and bit him on one of his ears,” the arrest affidavit states. “He wanted a toy.”

The brutality didn’t stop at the register. Surveillance cameras and witnesses watched her drag both young boys outside, where she proceeded to slap both of them across the face simultaneously on the sidewalk.

Even seasoned officers were shaken by the footage obtained by Local 10.

“Having to watch that video — that’s one of the most vicious videos that I’ve seen,” said Hialeah Police Lt. Eddie Rodriguez to Local 10. “That’s, in my opinion, a total betrayal of a mother’s love.”

Rodriguez noted that the tape carried audio as well as picture, amplifying the cruelty. “Heartbreaking to hear the screams that child felt,” he said. “You could tell the pain that he was going through.”

Officers tracked down Inurrieta-Martinez the following day, booking her on felony child abuse charges. A judge set her bond at $5,000, though federal authorities have since slapped an immigration hold on the Cuban national.

The aftermath has left the two young brothers facing an uncertain future. Child welfare agents swiftly removed both boys from her custody, but because they have different fathers, with one dad living outside the country, state officials warned the traumatized siblings may have to be split up.