A teacher was allegedly attacked by a parent in the hall of a Long Island middle school — and in a disturbing surveillance photo can be seen knocked out cold.

Teacher Catherine Engel­hardt was pummeled by a parent and a 14-year-old at the Alverta B. Gray Schultz Middle School in Hempsted Wednesday, police said.

“It’s not like I thought a parent would do something, but I knew something violent was going to happen,” Engelhardt told WABC/Channel 7 from her home.

“I’ve warned them time and again that the children have no respect for adults. Yes, I fear for my safety. They can’t control the kids.”

Irate mom Annika McKenzie allegedly pushed her way past security at the middle school to confront Engelhardt.

McKenzie was angry about an incident earlier in the day in which she claimed the teacher grabbed her 12-year-old daughter.

The teacher called security when McKenzie confronted her, and the mom allegedly went ballistic.

She allegedly put the teacher in a chokehold, shoved her into a wall and decked her, Channel 7 said.

Then some kids, including McKenzie’s daughter and 14-year-old niece, allegedly started kicking the teacher, the report said.

Engel­hardt was taken to Winthrop University Hospital and later released.

McKenzie was arrested and charged with felony strangulation and assault.

The 14-year-old girl was charged with assault, police sources said.