A three-year-old boy together with his 11-month-old brother were found in an apartment in the Bronx with multiple stab wounds in the neck and body area, after which they were taken to the hospital, but unfortunately the injuries were too severe and the doctors could not save them, US media reports.

Their 24-year-old mother was taken to the police and then taken to the hospital after, as reported by the media, she behaved strangely.

The mother has not been arrested, and the children's father has not been detained, the deputy head told journalists. But later the media reported that the mother was considered a suspect.

The police officers acted on a report of the woman's strange but non-violent behavior. Police were told the woman was trying to set things on fire in the kitchen, and they found her in the third-floor apartment. "She was acting irrationally," said the police.

She was detained without incident until the ambulance arrived and took her to the hospital for observation. Before going to the hospital, a family friend told the police that the children were with their father.

What happened next is not entirely clear.

Later, the police received a new complaint. At the same address, it was reported that two children were not breathing. Police say officers returned to the apartment and found the boys with multiple stab wounds.

Police officers and a family member tried to resuscitate the children while they waited for an ambulance, which took them to a hospital, where they died.

"Despite the best efforts of the police officers, the two children succumbed to their injuries," the deputy said.

Next door neighbor Shannon Holyfield said the boy's parents had argued earlier in the day. Later she heard the father scream and saw him carrying the two boys, naked and covered in blood, down the hall.

"He was screaming hysterically. He screamed – help me! I opened the door and saw him coming down the hall with the two boys in his arms. They were dead. There was blood everywhere," said the neighbor.