Jose Rivera, 48, told the New York Daily News that two other giant rats escaped.
"I hit it one time and it was still moving," Rivera said of the rat he stabbed at Marcy Houses. "I hit it another time and that's when it died. I'm not scared of rats but I was scared of being bitten."
Naomi Colon, head of the apartment complex's tenant association, told the Daily News huge rats have been sighted there for at least six years.
"The residents have told me that they've seen it running around with other rats," she said.
Animal experts said based on a photo of the dead rodent -- about 3 feet long from its nose to the tip of its tail -- it was a Gambian pouched rat, often kept as a pet, although imports have been outlawed for several years.
Paul Calle of the Wildlife Conservation Society said the Gambian rat can't reproduce with other species of rats because they are from a different genus.
The size of the Gambian rat has Marcy House residents unnerved.
"Even the cats are afraid of the rats. They get together and gang up on the cats," Stephanie Davis told the newspaper.