The NYPD is immediately stepping up patrols throughout the subway system after four homeless people were stabbed, two fatally, along the same train line within a span of 24 hours. Police are now combing through video surveillance and theorize three of the four stabbings could be the work of one killer.

At a news conference on Saturday at Police Headquarters, NYPD Commissioner Dermot Shea said 500 officers will be stationed throughout all 472 subway lines, including the A line where the series of stabbings occurred.

"They can expect to see a very large footprint of uniformed officers deployed throughout New York City, whether they go onto a train, whether they go onto a platform, and they'll be there as a long as needed," Shea said. "Five-hundred additional officers is a significant amount of resources added into the already thousands of officers already deployed by the NYPD."

Shea, joined by NYPD Transit Chief Kathleen O’Reilly and Deputy Chief of Detectives for northern Manhattan Brian McGee, said the officers will be redeployed from other assignments to help improve public safety throughout the system. Along with the extra officers, those already dispatched to stations—including plainclothes officers—are already working overtime to continue patrolling the system, according to police.

"The A line is probably going to be the safest line in the city," O'Reilly said.

The first stabbing occurred on Friday, when temperatures had hovered below freezing, which often sends New York’s homeless population seeking shelter in the subway. It was at around 11:20 a.m. at the Fort Washington-181st Street subway station, where a 67-year-old man was stabbed with a sharp object by another man, according to police. The victim survived the unprovoked attack and was rushed and treated at a local hospital.

At 11:20 p.m. on Friday, police were called to the Mott Avenue-Beach 22nd Street station in Far Rockaway, Queens where another man reported to be unconscious was found stabbed to death on a subway bench. The victim was pronounced dead at the scene. Two hours later, at the other end of the A line, a 44-year-old woman was found dead with stab wounds to the body and lying underneath a bench on a train at the West 207th Street and Broadway station. The victim, who had lacerations to her neck and body, was found by an MTA employee, according to McGee. The last incident happened back at the Fort Washington-181st Street station at around 1:15 a.m. where a 43-year-old man was found stabbed by a man he did not know. The attacker immediately fled the station. The victim survived the attack, and was hospitalized with stab wounds that McGee said required surgery.

Because the attacks all occurred on a specific train line and victims told police a man committed at least two of the incidents, police believe the same person is responsible for at least three of the attacks.

“We’re keeping all of our options open,” McGee said. “Two of the victims, we still have to do more further interviews so all this is preliminary.”

Police said a full description of the perpetrator will be released shortly.

"There is a small army of detectives and investigators working this all night, throughout New York City," Shea said.

The stabbings comes amid an increase in violent incidents against MTA workers and straphangers over the last few weeks.

In a statement responding to the police surge, New York City Transit interim president Sarah Feinberg welcomed the additional resources, calling them a "strong step forward" while emphasizing that the request for more officers on hand was made more than a year ago.

“We continue to face an acute mental health crisis that has been exacerbated by the pandemic and we need additional dedicated resources to address this challenge," Feinberg said.