Three masked men thought to be armed with an axe and a knife forced their way into a family home before making demands for jewellery and money.
The break-in caused a woman and her two sons to take refuge and call police in an upstairs bedroom.
Detectives are appealing for information after the burglary at 23.20pm in Staincliffe Road, Dewsbury, last night (Thursday).
The sleeping family were woken by the disruption as the culprits broke in, and a 35-year-old man confronted them.
He was assaulted and threatened with a knife, before having a ring snatched from his finger.
A 48-year-old woman and her two sons, aged 12 and 13, then took refuge in a bedroom, where she called the police before suspects made off in a silver coloured estate car.
One of the suspects was described as tall and slim, wearing a black balaclava with a dark coloured zip-up jacket, light coloured jeans with dark work-man style gloves.
Det Insp Andy Leonard, of Kirklees CID, said: “This has been a terrifying experience for the family being woken up by three masked men in their home.
“The male victim was assaulted and left with facial injuries as a result of the assault. “Although his partner and children were unhurt and remained upstairs while the assault took place, they were understandably very upset and frightened.
He added: “We do believe this was an isolated incident and are investigating the circumstances of what took place. The break-in occurred in a residential area, and whilst it was late, I am sure someone will have heard or seen something.
“I would appeal for anyone who has seen a silver estate vehicle in the area at the time of the offence, either on Staincliffe Road, or on Healds Road, to get in touch as they may hold vital information. Enquiries are ongoing.”
Anyone with information is asked to contact Kirklees CID on 101, or Crimestoppers anonymously on 0800 555 111.