Detectives are investigating after an aggravated burglary.
The offence is believed to have happened between 20:15hrs and 20:37hrs on Sunday, 10 February at a residential address in Pinner, Middlesex.
The victims - a man in his mid-30s, a woman in her late 50s and a man in his late 60s - reported that the door to their home had been forced and four male suspects had entered the house.
The suspects then threatened the householders with a large hunting knife and screwdriver and demanded valuables.
The victims were threatened they would be killed if they did not cooperate and one of the suspects punched the man in his 30s in the face causing swelling to his eye.
The suspects then left taking cash and jewellery.
The victims were left shocked, but did not require hospital treatment.
Officers were called at 20:38hrs.
Any witnesses or anyone with any information is asked to call police on 101 or contact via Twitter @MetCC. Quote CAD 6552/10FEB.
To give information anonymously contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org.