A gang of five or six men armed with baseball bats threatened a family and stole their car.
And in another incident a woman was pushed to the floor as a man escaped in her vehicle.
In the first attack, five or six men burst into a property on Thorncliffe Road, Batley, sometime between 9.30pm and 9.40pm on Thursday.
They forced a 53-year-old man and his children aged 20, 18 and 13 to lie on the floor and demanded money and jewellery.
Det Insp Ian Thornes, of Kirklees CID said: “They took a large amount of property from the house and the keys to a grey Audi A6 parked outside.
“They drove off in the vehicle and a silver Jaguar which we they arrived in. The Jaguar has been seized in Bradford.”
Earlier in the evening, a 23-year-old woman was pushed to the floor by a man who then stole her car.
Police said he went to the property on Ringshaw Drive in Gomersal sometime between 8.15pm and 8.30pm on Thursday.
The man asked the home owner if her name was “Sam” and if she had any puppies for sale.
When she said “no”, he knocked the woman to the floor and stole the keys to a red VW Golf 64 plate parked outside and drove off in the car.
The man is white, aged between 30 and 35, 5ft 5ins tall and of medium build.
He has short blond hair and wore a blue long sleeved top with the word Crufts written across the chest.
Police are investigating whether the two incidents are connected.
Anyone with information should call Kirklees CID on 101.