They stole a large amount of cash, along with jewellery, bank cards and a mobile phone and escaped in her husband's grey Range Rover, registration RF58 WYK.
The vehicle was found on fire next to a row of garages in Greenside Walk, Wortley at about 7.30pm last night.
Four men were seen running away before driving off in a brown Alfa Romeo with a 2015 registration plate.
Police say the car is believed to have been stolen from its owner at a farm off Whitehall Road, New Farnley, at about 6pm on Monday. It has the registration YC15 RJU.
During that incident the 74-year-old victim was knocked to the floor and had a knife held to his throat by up to six masked men.
They demanded money and stole cash, jewellery and a phone before leaving in the car.
The jewellery included a 9-carat gold necklace with a medallion and two elephants attached, a gold wedding ring, a silver ring with a tiger's eye and a gold-coloured Rotary watch with a brown strap.
Detective Inspector John Dexter, of Leeds District CID, said: "We are now treating these two incidents as linked and believe the same offenders have been involved. Given the violent nature of both offences, it is clear we are dealing with people who need to be taken off the streets at the earliest opportunity.
"We have had an excellent response from the public so far and we are continuing to appeal for information that could assist in identifying these men. We would like to hear from anyone who witnessed anything suspicious around the time of either incident as well as anyone who saw the men setting the Range Rover on fire in Wortley or driving away in the grey Alfa Romeo.
"The Alfa Romeo is still outstanding and we would like to hear from anyone who has seen that vehicle since it was stolen on Monday or who knows its current whereabouts.
"We have a team of detectives carrying out extensive enquiries into these incidents and we are looking at whether they are linked to any other similar offences.
"These incidents will understandably have caused concern in the community but I would like to reassure people that we are doing everything we can to find the people responsible and bring them to justice."
Anyone with any information is asked to contact Leeds District CID at Elland Road via 101 or call the independent charity Crimestoppers anonymously on 0800 555 111.