The attack happened at the Carnegie Skate Park, in Shipley
A man has been arrested on suspicion of murdering an elderly woman and the attempted murder of a boy at a park.
The nine-year-old boy was attacked on Monday at the Carnegie Skate Park in Shipley, West Yorkshire. He is said to be in a stable condition in hospital.
Police later found the body of 84-year-old Louisa Denby at her home in Prospect Mount. She had been stabbed.
A 26-year-old Shipley man, who police said was related to the woman, is being held in connection with both crimes.
Mrs Denby was found with "numerous stab wounds" just before midnight by police investigating the skate park attack.
West Yorkshire Police said the suspect was arrested after being spotted by a member of the public in Westfield Lane, Idle, in nearby Bradford, at about 04:10 BST.
'Massive police presence'
Another 26-year-old man is also being held in connection with Mrs Denby's murder.
Louisa Denby was found stabbed at her house in
A further three local men aged 18, 24 and 29 are being held in connection with the boy's stabbing.
All five men are in police custody.
The boy received chest and arm injuries in the attack, which happened at about 16:40.
Police said he was expected to have surgery at Leeds General Infirmary later.
Shipley councillor Vanda Greenwood, who was born in the area, said: "I have never known anything so horrific as this... it's just terrible."
She said there was a "massive police presence" in the area.
'Nice, normal lad'
The skate park is about 300m (1,000ft) from Prospect Mount, where Mrs Denby's body was found.
Both the park and the area around the house have been cordoned off, as well as a number of other locations in the Windhill area.
David Jacobs, who lives near Mrs Denby's house, said the community was "shell-shocked".
He said: "I know the little boy because he plays with my son, it's tragic.
"He's a very nice, normal lad who likes to play on his scooter and at the park and play on his bike."