A nine-year-old boy who was stabbed to death was a "normal little lad" according to neighbours who said his older brother had been arrested in connection with the incident.
The young victim was stabbed at a house in the Wibsey area of Bradford last night.
His 18-year-old sister was also injured, police said.
Today, neighbours spoke of their shock as details of the tragedy emerged.
Trevor Bairstow, whose 10-year-old granddaughter Leah went to school with the victim, said he was horrified.
Mr Bairstow confirmed it was boy’s adult brother who had been arrested in connection with the death.
He said: "(The boy) went to Wibsey Primary School. He was normal little lad. I used to see him playing out and about.
"He never bothered us. What can you say. He’s a nine-year-old boy who’s been stabbed. It’s shocking."
West Yorkshire Police confirmed a 20-year-old man had been arrested in connection with the incident.
A spokesman said officers were called at 7.46pm yesterday to a house on Rookes Avenue, Bradford, West Yorkshire, after reports of a stabbing.
Police said the boy was taken to Bradford Royal Infirmary by ambulance but died from his injuries shortly after 8pm.
His 18-year-old sister was also taken to hospital with a stab wound but her injuries are not believed to be life-threatening.
Police said a post-mortem examination showed the boy died as a result of multiple stab wounds.
A 20-year-old man in custody was arrested on suspicion of murder and assault, officers said.
Dale Webster, 24, who lives across the road from where the stabbing took place, spoke of his shock.
He described the victim as a "cute little lad" who came to collect sponsorship money from him a couple of months ago.
Mr Webster said: "That was the last time I saw him. He was a cute little lad. He was just a normal kid.
"I used to see him playing on his bike a lot. He came one day and asked me to sponsor him for school."
He said the street was usually quiet and peaceful but he added: "I’ve seen police go into that house a lot in the past. And I think a mental health team have gone to the home."
Mr Webster said he was shocked by the stabbing.
"I saw a police van outside the house last night," he said. "I didn’t think much of it.
"There was no noise or anything like that. But then I heard about it on the TV this morning. It’s appalling."
There was a substantial police presence on the estate today.
Five houses between Rookes Avenue and Richardson Avenue were cordoned off by police tape.
Officers guarded the front and back doors of a house on Richardson Avenue, adjacent to Rookes Avenue, while two stood at the top of a nearby alleyway.
Four houses on Rookes Avenue were also included in the cordon.
Three police vehicles - a video van, police van and car - were parked in the estate.
The street was fairly quiet with only a few neighbours looking out of their windows at the police and gathered media.