A 44-year-old man has been arrested on suspicion of murder following the stabbing of an Irish pensioner who was on a mobility scooter in West London.
Thomas O'Halloran was attacked in Greenford on Tuesday afternoon.
It is understood that he attempted to flee the scene to seek help following the incident but was later pronounced dead.
The 87-year-old, who lived in London for most of his life, is from Ennistymon in Co Clare.
Local senator Martin Conway says Thomas kept Clare close to his heart while living abroad.
"It's such appalling circumstances that has very much shocked the community of Ennistymon and indeed throughout the County," Mr. Conway said.
"People are still processing what happened, how it could happen and why it happened.
"That somebody of such a senior age, 87, using a mobility scooter would be attacked in such a violent and brutal way."
Mayor of London, Sadiq Khan, released a statement on his social media a short time ago: "It’s devastating that 87-year-old Thomas O’Halloran was killed on Tuesday afternoon.
"My thoughts are with his friends, family and local community.
"Today I visited officers in Acton police station and was briefed about additional patrols that are taking place in the area."
"This morning a 44-year-old man was arrested on suspicion of murder and remains in custody," he added.
"If you have any information or video footage of the area, please contact the @metpoliceUK or @crimestoppersuk as soon as possible: http://crimestoppers-uk.org"