Police have launched an arson investigation after six people were forced to flee a house fire in Dewsbury.
He remains in hospital, although his injuries are not thought to be life threatening.
The five other occupants needed medical treatment.
Several other properties were also evacuated after the fire spread to neighbouring homes.
West Yorkshire Police's Homicide and Major Enquiry Team is investigating.
Det Chief Insp Sharron Kaye said: "We do believe this fire was started deliberately and given there were a number of people in the house at the time this is a serious incident.
"Police and specialist investigators remain at the property today which was very heavily damaged and, as such, not safe to search yesterday."
She added: "It is important we locate and arrest the parties responsible for this extremely dangerous act."
The detective appealed for anyone who saw any suspicious activity outside the property or anyone with information to come forward by calling police on 101 or Crimestoppers on 0800 555111.