A MOM allegedly beat a 14-year-old over the head with a Stanley cup in a shocking fight caught on video.

The teen was left bloodied and needed stitches as stunned students looked on.

The brawl erupted outside Brentwood High School on Long Island during summer classes on Tuesday morning.

Police say the attacker was the 35-year-old mother of a student who had been arguing with the victim.

Suffolk County Police identified the parent as Toni Monroe, ABC local affiliate WABC reported.

Cops allege Monroe struck the girl several times with a metal water bottle.

Cellphone video recorded by the victim’s cousin shows tensions flaring as two students argue.

Security tried to keep them apart, but the confrontation spilled outside.

In the clip, Monroe is heard telling her daughter, ” “Give me your Stanley,” before stepping in.

Video then shows a woman in a yellow tank top hitting the 14-year-old wearing a lavender shirt.

“Her mom just came in and started beating me with the cup,” the victim, Madison Evans, said.

“I took my head because I saw blood dripping. I took my head and I saw blood all over my hands.”

Evans said she needed 17 stitches to close a gash on her forehead and the recovery has been painful.

She is about to start 10th grade at Brentwood High School.

Police arrested Monroe in the school parking lot a short time later.

She appeared in First District Court in Central Islip on Wednesday.

Prosecutors charged her with two felony counts of second-degree assault and endangering the welfare of a child.

The judge released Monroe with a GPS monitor and issued an order of protection keeping her away from Evans.

Officials noted Monroe has no prior criminal history.

Her defense attorney denied she punched the teen.

He argued Monroe was at school for a meeting about bullying and that Evans and others had targeted her daughter.

He claimed Evans attacked the 15-year-old first.

Evans said the dispute began as a verbal argument before Monroe jumped in.

Brentwood Superintendent of Schools Wanda Ortiz-Rivera told families: “We are aware of the incident that occurred yesterday during dismissal involving two students and a parent.”

“The safety and well-being of our students is always our highest priority, and this type of behavior is unacceptable and will not be tolerated in our schools.”

“As a mom, you are supposed to diffuse the situation and take your daughter away to see what’s going on, instead of attacking a kid with a cup,” Evans’ cousin Tyleen Smith said.

“She could’ve died. Anything could’ve happened to her, more than just being hit over the head and having 17 stitches,” added Evans’ guardian, Shameakca Forney.