A mother screamed for help "like she was being tortured" at a home where a one-year-old girl and a boy aged three were stabbed to death, a neighbour has said.

The children were killed in the "devastating and horrific" attack in Ilford, east London, as police and the air ambulance went to the scene at about 5.30pm on Sunday.

A 40-year-old man who was known to the children is fighting for his life in hospital after suffering knife wounds, Scotland Yard said, adding detectives have launched a murder investigation but are not looking for anyone else over the killings.

A newsagent worker named locally as Nithin Kumar, known as Nithi, lives at the property with his wife Nisa and two young children, reporters were told.

His boss Shanmugathas Thevadurai told reporters at the CVS store about two miles from the scene: "He's my staff. Yesterday he was working here normally, he came and opened the shop and finished around 4pm."

He added that he did not believe it when he went to the house and saw police and ambulances.

Mr Thevadurai, 54, said he hired Mr Kumar eight years ago after he lost his job at Tesco, and called him a "hard-working, honest person" who had a "shy" disposition but was "very polite and friendly with customers" and would sometimes call his family on the phone at work.

The toddler died at the scene in Aldborough Road North, which is just yards from a day nursery, while the boy died later in hospital, Scotland Yard said.

A mother-of-two who lives across the road and gave her name as Reshna told the PA news agency: "I heard a woman screaming 'Help me'.

"It sounded like she was being tortured. I knew something horrible must have happened, it went on for about 10 minutes."

The neighbour said she later saw medics carrying a "little body" in a bag outside.

She added: "My heart just sank, it's devastating, horrific. From a mother's perspective - I'm still shaken from it, I can't imagine what she feels at the moment."

Police were seen patrolling a cordon encircling two newsagents attached to some flats in the quiet residential road off the A12 on Monday.

Two small toy rabbits, one blue and one white and pink, were left at the scene with a note saying: "Little angels, we are so sorry. Rest in Peace."

Several neighbours said the family were of Sri Lankan descent.

Neighbour Intisar Ahmed said they had lived there for around two years and that she saw a police officer take one of the injured children outside and attempt CPR.

She said: "I was so, so upset. I couldn't believe it, the baby on the floor and the policeman trying first aid.

"I saw them put him on the floor and it looks like they had taken the clothes off. I could hear the mother screaming."

A Scotland Yard spokesman said: "The children's next of kin have been informed.

"A 40-year-old man was also taken to hospital and is in a critical condition; officers remain in attendance at the hospital.

"It is believed that all parties involved were known to each other; all three had suffered knife injuries.

"Although no formal arrest has been made, at this early stage, police are not currently looking for anyone else in connection with this incident."

By Thomas Hornall, PA