A 44-year-old woman, nine-year-old girl and five-year-old boy travelling in a grey motorhome were pronounced dead at the scene of the crash with a lorry on August 24, near the Jinnah restaurant.
A six-year-old boy was taken to hospital with a serious head injury and the 48-year-old man driving the motorhome was also seriously hurt.
Police Sergeant Paul Cording said that the six-year-old boy and his dad have been allowed to return home from hospital, only to discover that thieves had ransacked the house.
He said they had "taken everything", including a TV, Xbox and sentimental items which can never be replaced.
A group of North Yorkshire Police officers and other emergency services staff have now created a GoFundMe page to raise money to help the family replace their possessions.
Mr Cording said: "We are horrified with what has taken place and can’t just sit by and do nothing.
"We have started a collection to replace some of the items and if you would like to help this family try to rebuild their lives then please do donate if you can."
Mr Cording said that the family are from the wider Yorkshire area and that investigations into the crash and burglary are ongoing.
You can donate to the GoFundMe page here, which has raised more than £900 in less than two hours.