Edwin Rivera was woken up early on Sunday morning by loud thuds coming from the floor above him. He thought it was probably a fist fight.
After getting out of his bed in the homeless shelter on the Upper West Side of Manhattan, Mr. Rivera went upstairs to break up the brawl and found a gruesome scene: Blood was splattered on the walls, and one of the men who had been fighting was gasping for life.
“It was horrible — I see him dying and I’m there trying to revive him,” Mr. Rivera, 40, said.
The fight, which happened at around 1:50 a.m. at Basics Housing Men’s Homeless Shelter, ended with a 22-year-old man dead and his 36-year-old roommate, who also sustained stab wounds, in the hospital in stable condition, according to the police.
The police said they were investigating the episode, but believe the younger man, Geronal Washington, tried to stab his roommate, Robert Caballero, who then took the blade from him and killed him.
The episode was the second fatal stabbing in a week involving a homeless man in New York City: On Nov. 5, a 38-year-old was stabbed to death outside a shelter in East Elmhurst, Queens.
Both attacks have spotlighted the violence endemic to the shelter system and the challenges the city has faced in trying to curb it across over 400 of its shelters, despite efforts to overhaul security at these facilities in recent years.
Mr. Washington’s death has also added renewed scrutiny to the nonprofit, Acacia Network Housing Inc., that operates the shelter where he was stabbed. Acacia is one of the largest providers of homeless housing in New York City and has been mired in controversy over its security practices.
In July, The Wall Street Journal reported that the nonprofit’s executives had failed to disclose ties to a for-profit security company, SERA Security Services, that it had hired to provide security at some of the shelters. The city then began investigating Acacia, which has received hundreds of millions of dollars in contracts from the city since 2010.
But the fatal attack on Sunday at the Acacia-run shelter — where city officials say SERA provides security — has led to renewed calls for New York to more urgently address concerns about the nonprofit. Acacia operates 750 individual family housing units as well as four shelters that house 550 homeless adults in the city, according to the department.
“There is a real problem here and we need to do something before another life is lost,” said Councilman Ben Kallos, chairman of the City Council’s contracting committee.
Mr. Kallos, a Democrat, says he plans to call on Monday for a Council hearing regarding Acacia’s practices.
Since the nonprofit came under investigation, Mr. Kallos said several current and former residents in Acacia shelters had shared stories of their troubling experiences: Some told him they were forced to share rooms with other residents who had threatened to kill them or had previously injured them. Others said Acacia staff members had threatened to evict them if they called the police about the conditions inside the shelter.
“One of the hardest problems is that the people in these shelters and making these reports are those who the system and society might not treat as credible,” Mr. Kallos said. “But in light of what happened yesterday, that seems less and less the case.”
A spokesman for Acacia said on Sunday night that staff members at the shelter immediately notified the police after the attack and were working with police investigators. “We are deeply saddened by the tragedy that took place,” he said. “Guards patrol this 103-unit shelter around the clock and violence is extremely rare, as this is the first violent incident recorded there all year.”
For decades, the city’s shelter system has been notorious for the dangerous conditions at some of its sites, particularly at intake and assessment centers — the system’s front door. Those threats are often the reason homeless people prefer to stay on the streets or in subway cars, instead of at shelters.
“There are fights, there is drug use, there are gangs, you name it,” said Nikita Price, a civil rights organizer with Picture the Homeless, an advocacy organization led by homeless people. “You put all these elements together, it is going to get volatile.”
But safety for people living on the street can be just as elusive: Last month, a homeless man in Chinatown bludgeoned four other homeless men to death in a rampage that spread new anxiety among the city’s homeless population.
The violence at shelters made headlines in 2016 after a string of deaths at city sites, including the murder of a young mother and two of her daughters on Staten Island.
In response to the deaths, the Department of Homeless Services and the Police Department overhauled security at these facilities, developing a police-led management team to oversee security and creating new training for the system’s peace guards, the city-employed security officers who have arresting powers but do not carry guns.
Over the past year, data from the Police Department suggests crime at homeless shelters is declining. In the first half of this year, the police made 1,084 arrests in shelters, down 17 percent from the 1,313 arrests made in shelters over the same period last year.
Still, many of the city’s homeless people and their advocates say that addressing the dangers embedded in the system requires more than just bolstering law enforcement at the shelters.
“Homeless New Yorkers tell us shelter security is often too lax and that reporting incidents to staff can often make matters worse,” said Josh Dean, executive director of Human.nyc, a policy organization that focuses on homelessness. “The best way to keep people safe is to invest in housing and then provide ongoing supportive services when necessary. Shelters are never going to be safer than real housing.”
James Little, 64, who has lived for about a year at the shelter where the stabbing occurred on Sunday morning, said Basics Housing usually felt safer than others he had lived in.
Mr. Little said that he had only one roommate at the shelter — compared with 10 to 12 at other locations — and that he could lock the door from the inside.
“You come from the other places and you come here and you relax,” Mr. Little said. “But then you hear things like this happen and you’re not sure how safe you are.”