A six-month-old baby was being treated in hospital last night as her parents were being held by police over the stabbing to death of her young brother and sister at their suburban home.

The baby was said to be in a critical but stable condition after surgery. Her father, named as Navarajah Navaneethan, 39, was being questioned at a police station near the family home in Carshalton, Surrey, over the attacks in which her five-year-old brother and four-year-old sister suffered knife wounds. They were pronounced dead in hospital within minutes of each other. The childrens’ mother, Sasikala, 35, was in hospital being treated for minor injuries and was expected to be kept in overnight. She has not been questioned yet.

One neighbour described the “horrific” scene as paramedics tried to revive a “little limp body” after being called to the three-bedroom house just after 10.30pm on Friday.

Jim Knight, another neighbour, said: “We saw them bringing a child out and then about half an hour later they came out with another child; then a woman who had blood on her dress, on her back. They took her into an ambulance, not a police car.”

Scotland Yard said a man aged 39 and a 35-year-old woman were being held.

John Bailey, who had been visiting a neighbouring house, said: “Six policemen were running up and down the road. They didn’t seem to know what house they had been called to. An Asian-looking man just walked out of the house.

“He was just standing there on the other side of the road. He didn’t show any emotion. It was as though he was frozen.

“I saw a child being carried out in a white sheet. The sheet was practically all red — completely soaked in blood. The paramedic placed her on a bed in the ambulance and was trying to resuscitate her.”

Sen Gupta, a neighbour, said that the arrested couple were from Sri Lanka. Gupta said that friends or relatives of the couple arrived after the police.

“They said that they had lived in the house with the couple but moved out because of problems. The police came out and spoke to them.

“They must have been telling them that the children had died because they started screaming and crying.”

Times Recommends

• Swine flu vaccine for all as drug rushed through
• Artificial sperm and the race to build a baby
• BBC jets out stars to tout for prizes