A five-year-old boy and a four-year-old girl died in hospital after being found injured at their home in Carshalton, south-east London. A six-month-old girl was found in the same house with stab injuries and was operated on in hospital. Her condition was critical but stable.

The couple, a 39-year-old man and a 35-year-old woman, are believed to be parents of all three children and are being held at police stations in the capital.

Neighbours described paramedics carrying the children out of the two-bedroom detached house in Park Lane just after 10.30pm on Friday night.

One told of an "horrific" scene as paramedics tried to revive a "limp little body". The woman, who did not want to be named, saw a "tiny bundle" carried out of the suburban home. "It was obviously a child," she said. "It's horrific for something like this to happen here."

The £300,000 two-bedroom property was taped off as officers carried out an examination of the scene. Neighbours said the couple were thought to be from the Tamil areas of Sri Lanka and had moved to the suburb in the last year.

Sen Gupta, who lives opposite, described seeing friends or relatives crying and screaming when they learnt of the deaths.

"When it happened a group of people, also Sri Lankan, came to the house very soon after the police arrived.

"They were pacing up and down outside for a while. They said 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 the children had died because they started screaming and crying."

A spokesman for the Metropolitan Police said officers were called to the house at 10.30pm. Post-mortem examinations on the two victims are expected to be carried out early next week.