It happened near the corner of Stuyvesant Avenue and Kosciuszko Street in Bedford-Stuyvesant around 12:45 a.m. Friday.
Police remained on the scene hours later investigating.
Police said the 61-year-old was trying to break up a fight between some young men.
During that fight, she got stabbed in the chest.
The commotion and sound woke up neighbors.
"About midnight I heard a bunch of fighting and I decided to go back inside," one neighbor said.
"In the summertime, about twice a week, we have this kind of thing," another neighbor said. "There was also a shooting at the bodega up the street and someone was shot to death."
She was taken to Kings County Hospital where she was treated for what appeared to be non-life threatening injuries.
The young men who were fighting apparently ran away.
So far, there are no arrests.
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