NEW YORK — When relatives of a Chinese immigrant mother of four young children banged on the family’s door, it opened to a grisly sight: a man dripping with human blood who is now charged with stabbing the five to death with a butcher knife.

Mingdong Chen, 25, faced five counts of murder Sunday, a day after the brutal killings of his cousin’s wife and her four children in Brooklyn’s Sunset Park neighborhood.

Two girls, 9-year-old Linda Zhuo and 7-year-old Amy Zhuo, were pronounced dead at the scene, along with the youngest child, 18-month-old William Zhuo — all found in a back bedroom, police said. Their brother, 5-year-old Kevin Zhuo, and 37-year-old mother, Qiao Zhen Li, were found in the kitchen and taken to hospitals, where they also were pronounced dead.

The five “were cut and butchered with a kitchen knife,” said Chief of Department Philip Banks III, the New York Police Department’s highest-ranking uniformed member.