A three-year-old boy has died and another boy, 4, has suffered life-threatening injuries in a shed fire in northern Tasmania.

Emergency services were called to the blaze at a home in the Launceston suburb of Mowbray around 1.30pm on Wednesday.

The three-year-old was found dead at the scene, while the four-year-old was rushed to hospital along with a woman who was seriously injured.

Tasmania Police Inspector Nathan Johnston said the woman was related to the boy who died.

“Due to the nature of this investigation … we can’t really elaborate at this point in time about what has actually occurred,” he told reporters.

It is believed both boys were in the shed. There were other people at the house at the time.

Insp Johnston said the family was distraught.

“It’s a tragic set of circumstances. We don’t know the full story at this point,” he said.

He said the boys weren’t siblings but knew each other.

The shed was “fully alight” when fire crews arrived, Tasmania Police said.

Authorities will conduct an investigation to determine the cause of the fire and a report will be prepared for the coroner.

– AAP