A major homicide investigation is underway after a man believed to be in his 60s was found dead outside a burning home in Glenmore Park, in Sydney's west, during the early hours of Thursday morning. Emergency services were called to a property on Wargon Crescent shortly before 1:00am after reports of a house fire.

Firefighters extinguished the blaze and discovered the man's body in the carport area of the property. Police said the victim had suffered significant burn injuries as well as other injuries, prompting detectives to treat the death as suspicious. A crime scene has since been established while forensic specialists examine the property.

Investigators believe the incident began after an alleged break and enter at the home. Police allege the property's front door had been forced open and that an altercation occurred before a fire was deliberately lit. Detectives also believe an accelerant may have been used to ignite a blue Holden Commodore, with the flames spreading from the vehicle to the house.

At about 6:45am, officers located and arrested a 36-year-old man in nearby Werrington. Police believe the man is related to the deceased but was not living at the Glenmore Park address. He was found inside a vehicle with minor injuries and was taken to Nepean Hospital, where he remains under police guard.

As of Thursday, no charges had been laid. Police said investigators are awaiting post-mortem and forensic examination results to determine the exact cause of death and the circumstances leading to the fire.

Detectives are appealing for anyone who was in the Glenmore Park or Werrington areas during the early hours of Thursday, or who has CCTV, dashcam or other relevant footage, to contact Crime Stoppers or NSW Police. The investigation remains ongoing.