A neighbour and her three children were talking to a man minutes before a gas cylinder exploded and killed him, north of Brisbane, on Friday afternoon.

Emergency services said the man in his fifties was killed when a gas cylinder exploded in his backyard in Warner, making a loud bang that was heard across a wide area.

Ric Hartman, whose wife and kids were talking to the victim shortly beforehand, said he heard the explosion as he worked in his home office.

"There was a massive explosion, nothing like I can explain in terms of the sound and the intensity," Mr Hartman said.

"I jumped up, tried to find out what the cause was and then I saw our neighbour through the window who was lying on the ground, obviously in a very bad way."

Equipment from the man's shed gathered together by police. ( ABC News )

Mr Hartman rang emergency services and directed them to the scene, as the man's family were not at the house at the time.

"My wife and three children were out talking to him about five minutes before it happened," he said.

Mr Hartman described the man as a kind-hearted builder who worked and did well by his family.

"It's pretty close to home and obviously very tragic for their family," he said.

"We've been here for 15 years, they've been here longer. Our kids play and feed their guinea pigs of an afternoon, they're just beautiful people."

Police outside the home on Warner Road where the explosion occurred. ( ABC News )

Senior Sergeant Jeff Lansdown said the man's family arrived home shortly after the fatal explosion.

"The incident is quite catastrophic unfortunately, very traumatising for the family and also for all the emergency services personnel attending," he said.

"Police established a gentleman at the address had been involved in an incident where he was using some machinery beside his shed and the explosion had occurred as a result.

"He regularly used the equipment he was using at the time and the explosion was certainly unexpected."

Police are not treating the man's death as suspicious and a report is being prepared for the coroner.