A string of stabbing attacks has appeared in New York City, targeting homeless people. The New York Police Department has deployed hundreds of more officers to the subway system on Saturday following the series of attacks.

Four attacks have been identified by the New York City Police so far, with the first of those being on Friday morning when a 67-year-old man was stabbed at the West 181st street in upper Manhattan.

Late Friday another man was found dead on the train at Far Rockaway-Mott Avenue station in Queens. 

A 44-year old woman was found stabbed and was discovered unconscious on a train at the 207th street station in Manhattan, who was pronounced dead at the hospital.

At the West 181st street Station a 43-year-old man was stabbed, early Saturday.

The 67-year-old and the 43-year-old are recovering at the hospital.

Detectives say they are investigating whether or not the crimes were committed by the same person.

Dermot Shea, New York City Police Commissioner, said that the NYPD has immediately deployed 500 additional officers to the transit system of New York City in the wake of the incident.

"Bottom line that the public should know is this: They can expect to see a very large footprint of uniformed officers," Shea told reporters at a news conference. "Whether they go onto a train, whether they go onto a platform, and they'll be there as long as needed to make sure people feel safe."

A 24-year-old man was arrested in October 2019 for using a metal pipe to beat four homeless people to death as they slept in the city's Chinatown district.