Samantha Mills, who was 31 and from the Huddersfield area, and Reece Schofield, 24, from Dewsbury, were two of six people taken to hospital following the blaze at a house in Clare Hill on Tuesday, March 23.
Ms Mills sadly died in hospital on Friday.
Mr Schofield tragically died in hospital today (Monday).
Another person remains in hospital in a stable condition.
Craig Collier, 34, of Clare Hill in Huddersfield, has been charged with arson with intent to endanger life and perverting the course of justice.
He has since appeared at magistrates and has been remanded in custody ahead of a further hearing at Leeds Crown Court.
West Yorkshire Police’s Homicide and Major Enquiry Team is continuing to appeal to anyone who was in the Clare Hill area at about 6am on Tuesday March 23, to contact them on 101, quoting crime reference number 13210144132.
Information can also be reported anonymously to the independent charity Crimestoppers.