Police are searching for the person responsible for stabbing a Mount Vernon school custodian during a robbery off school grounds early Tuesday.

They say the victim is a custodian at Edward Williams School who was walking down the block to get lunch when he was approached by the suspect, according to the school district.

Police say 44-year-old Derek Fox was stabbed in his back and arm after refusing to give the suspect money near 36 West Fifth St. 

Witnesses tell News 12 they called the police after he ended up outside a bodega on West Fifth and South 8th Avenue and was bleeding.

"He needed help. He was bleeding. I called the authorities,” said Mount Vernon resident Jewel Page.

Fox was taken to Jacobi Medical Center in the Bronx where he has been stabilized, according to the school district.

The Williams School was placed into a heightened state of security, and the nearby Cecil H. Parker Elementary School was placed on lockout because of how close the incident was to the campus.

The incident shocked both faculty and student’s parents.

"It's anxiety-triggering just to know what's going on. It's like a trend now and I'm not sure what safety precautions they have, but something has to change,” said parent Natalee Campbell.

"We're hoping he recovers quickly,” said Mount Vernon acting school Superintendent, Dr. K. Veronica Smith

School district officials acknowledged the incident during a Board of Education meeting, but they did not say if there will be an increase in security Wednesday because it occurred off campus.