Queensland Police were called to Edmund Rice Drive at Southport on the Gold Coast about 9.35am yesterday after reports of an explosion.
“Upon arrival, officers located a man who informed them he had picked up an object before being injured,” a spokeswoman said today.
“Paramedics treated the man at the scene for very minor burns to his hands.”
The man also sustained minor injuries to his abdomen and pelvis.
He had been walking his three dogs at the time of the incident.
Nine reported the man had believed the black item was a toolbox and carried it for 500 metres from the home improvement warehouse on Olsen Ave.
The distance spans a six-lane road and included passing shops, churches and a primary school.
The Explosive Ordnance Response Team attended and deemed the device “inert”.
The Guardian Angels Primary School and a neighbouring aged care centre were locked down but police concluded there was no longer any risk to the public safety.
“It appears that it’s a single-shot firearm,” Inspector Barry Smith told Nine yesterday.
“When it discharged, it actually deactivated itself.”
Investigations are continuing.
Bunnings has been contacted for comment.