Bedfordshire Police are investigating two incidents of older people being assaulted by offenders stealing gold jewellery from Asian families.
The first happened on the afternoon of 2 August at Seamons Close, Dunstable.
A 72-year-old woman answered the door to a man who asked for Chris.
She said he must have the wrong house and he left.
She went upstairs and when she came back down the man was in the kitchen.
Two others were also in the house, both in balaclava type masks.
They demanded gold and threatened her with a knife.
Several items of jewellery were taken.
Meanwhile, the woman was tied up in her bedroom.
Two hours later, a 77-year-old man in Luton, answered the door to a man who asked if he needed any gardening doing.
Two others entered by the back door and demanded gold from him, threatening him with a screwdriver and hitting him with a stick.