Police say the victim, identified as Alfred Soto, was stabbed in the stomach and chest inside a West 96th Street building at around 10:20 a.m. where he also lives.
They say the stabbing occurred on the sixth floor inside an apartment.
John Somwar said his cousin, Soto, answered a call to help a friend and paid with his life.
Police said four to five men burst into a 6th-floor apartment this morning terrorizing a 19-year-old girl who had been watching her special needs brother.
Police said the men forced their way into the apartment to take a number of dogs.
The teen called her mom who then called Soto, her longtime neighbor, and lived a few floors upstairs.
Soto, who lived on the 11th floor, ran to the 6th floor to confront the attackers, but in the confrontation, he was stabbed twice.
"He went to diffuse a problem and it escalated and for him trying to be a good guy he got stabbed and killed," Frank Ramirez, the victim's friend said.
Police said the men fled the building in a U-Haul with no license plates.
Police arrived to find the victim bleeding heavily.
"He just dropped his phone, and I'll be right back and left. It was a friend that was in need and didn't feel safe that her daughter and she called him and knew he's the type of person that would step up and meet a challenge head-on," Somwar said.
EMS rushed him to the hospital but he was pronounced dead at Mount Sinai Morningside.
"All you needed was a phone call and he dropped everything, went downstairs, didn't matter, disregarded and he just tried to protect a young lady that he felt was threatened. Her mother called him and he just reacted. He was a good man in my opinion. He was a hero," Somwar said.
So far no one is in custody.
This story will be updated as more information becomes available.
----------
* Get Eyewitness News Delivered
* More Manhattan news
* Send us a news tip
* Download the abc7NY app for breaking news alerts
* Follow us on YouTube