Authorities say it happened around 8:45 a.m. after a dispute with another person in front of Westinghouse Career and Technical High School.
He was found injured at 3 MetroTech.
The victim was taken to Brooklyn Hospital in serious but stable condition.
So far, there are no arrests.
The Department of Education issued the following statement:
"The NYPD immediately responded to an off-site incident this morning, and we are working with them as they conduct a thorough investigation. Safety always comes first, and out of an abundance of caution there is additional security in place at the nearby campus. We will provide the school community with any needed support."
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