Teenagers attacked two men by throwing paving slabs at them outside a house in Livingston.
Police are appealing for information following the “unacceptable assault”.
A group of teenagers were seen throwing stones at a house in Falcon Brae around 5.30pm on Monday 10 April.
Two men challenged the youths and were subsequently assaulted with pieces of broken paving slabs.
The 27-year-old sustained head injuries and was taken to St John’s Hospital.
The 32-year-old sustained minor injuries to his forearm but did not require medical treatment.
Officers are appealing for the public’s help to trace the group and are eager to trace two males in particular.
The first is described as 15 - 17 years old, 5ft 10ins tall, of slim build, with short light-coloured hair, wearing a grey hooded top and grey jogging bottoms.
The second is described as 15 - 17 years old, 5ft 8ins tall, of slim build, with short light-brown hair, wearing a blue Diadora top and grey jogging bottoms.
Livingston Community Officer PC John McLean said:
“This behaviour is absolutely unacceptable and we’re appealing for the public’s help as part of our ongoing investigation.
“Anyone who may have seen the group in the area, recognises the descriptions of the two males, or has any information about this is urged to get in touch.”
Those with information can contact Police Scotland on 101 or report this anonymously to Crimestoppers on 0800 555