NEW YORK (CBSNewYork) — The NYPD is investigating a series of stabbings in the subway that left two people dead and two others hurt.

All four happened within 24 hours on the A train line.

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Around 11:20 a.m. Friday at the 181st Street A station, a 67-year-old man was stabbed and survived. He told police the attacker, who he did not know, said to him, “You are going to die.”

Friday night, about 12 hours after the first incident, a man was found stabbed to death on a train at the Mott Avenue-Far Rockaway station.

Just before 1:30 a.m. Saturday, a 43-year-old man was stabbed at the 181st Street station. He survived the attack.

A witness told CBS2’s Cory James the victim frantically raced over to him, opened up his jacket and showed him his injuries.

“He said he was stabbed on the A train,” the witness said. “It was multiple stab wounds on the back, and he was, like, gushing blood … As I went to ask him, he fell on the floor and he was unresponsive, so I called the police.”

He’s thankful the man he helped survived, but he hopes whoever is responsible is caught soon.

“I hope they find whoever did this. It’s just something that shouldn’t happen,” he said.

Watch Dave Carlin’s report —

Minutes later, police found a 44-year-old woman with stab wounds on an A train at the West 207th Street and Broadway station in Washington Heights. She was pronounced dead at the scene.

She has been identified as Claudine Roberts. A family member spoke to CBS2 through the window of their Brooklyn apartment but did not want to be identified.

“Claudine was a quiet girl. She don’t talk. She don’t keep friends,” the family member said. “I can’t deal with this. I can’t deal with this.”

“Three of these incidents appear to be connected and the Detective Bureau is looking into the possibility that all four could have been committed by one individual,” said NYPD Transit Chief Kathleen O’Reilly.

READ MORE: One Man Punched And Stabbed, Another Pushed Onto Platform In Latest Subway Attacks

“To the victims and to the victims’ families, we are 100% committed to getting justice,” NYPD Commissioner Dermot Shea said.

Police have released what they call a very preliminary description of the suspect.

“A male, light-skinned … About 5 foot tall, and he had a mask on, a face mask,” said Manhattan North Detective Bureau Assistant Chief Brian McGee.

Police said Saturday night that they were questioning a person of interest. No one has been charged at this time.

Investigators say identifying all the victims is complicated because they are all described as homeless, CBS2’s Dave Carlin reports.

Subway riders are disturbed by the attacks.

“It has never been so bad that now I’m really scared to go on my own,” one woman said.

The NYPD is beefing up its presence throughout the subway system in response.

“We will immediately commence a surge of officers to patrol both above and below ground,” Shea said. “This surge will result in an additional 500 officers.”

“Until this individual is apprehended, the A line is probably going to be the safest line in the city,” O’Reilly said.

Saturday evening, interim New York City Transit President Sarah Fienberg released the following statement:

“More than a year ago, Governor Cuomo and the MTA Board called for an increased police presence across our system to keep our employees and the riding public safe, and we’re glad the City and NYPD have agreed to add 500 additional NYPD officers to the system. The recent horrifying attacks demonstrate that these officers are a strong step forward, but more must be done. 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.”

The Coalition for the Homeless released a statement condemning the attacks and urging the city and state to “provide real and immediate access to housing for unsheltered New Yorkers.”

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CBS2’s Dave Carlin and Cory James contributed to this report.

CBSNewYork Team