Police say a 19-year-old woman was found fatally stabbed outside an apartment building in Inwood Monday afternoon, and a man is in custody in connection with her death.

Police responded to a 911 call for a woman stabbed in front of 75 Thayer St. just before 4 p.m. and found the victim unconscious. The woman was taken to Columbia Presbyterian Hospital, where she was pronounced dead.

Witnesses said the suspect stabbed the woman, ran to a nearby park and then stabbed himself. Bystanders ran after the man until police arrived.

"The girl was screaming for her life," said a witness, who only gave his first name, Manny . "She lost so much blood."

Police said they have the 21-year-old suspect in custody. It appears he and the victim knew each other.