A Far North Queensland man has been charged with grievous bodily harm and firearm offences after his son found his pistol and accidentally shot his little sister.

Key points: Detective Acting Inspector Kev Goan says the gun was left unsecured in reach of the children

Detective Acting Inspector Kev Goan says the gun was left unsecured in reach of the children The little girl was shot in the shoulder and is in a stable condition in Cairns Hospital

The little girl was shot in the shoulder and is in a stable condition in Cairns Hospital Acting Inspector Goan says it is a "tragic reminder" weapons need proper storage

The six-year-old girl was shot by her nine-year-old brother in their Cairns home last Friday.

On Monday, police charged their 47-year-old father, who allegedly left the 9mm Glock pistol unattended in a bedroom of their Earlville house.

Detective Acting Inspector Kev Goan said the girl was shot in the shoulder, but was lucky to avoid more serious wounding.

The girl was taken to Cairns Hospital in a stable condition.

A Glock pistol similar to this was picked up by a nine-year-old boy who accidentally shot his sister. ( NSW Police Force )

"The young girl is very fortunate to have avoided the catastrophe that you would expect with this," Acting Inspector Goan said.

"Her prognosis for recovery is reasonable, although we suspect there is going to be ongoing damage caused to her from the firearm."

Inspector Goan said the father was cleaning the pistol, for which he held the proper licence.

"He had to attend to other matters and the firearm was left unsecured and in reach of the young children," he said.

The father was charged with one count each of grievous bodily harm, failure to keep a weapon unloaded, failure to keep a weapon secure and other weapons-related offences.

He is due to appear in Cairns Magistrates Court on June 13.

Police said the man allegedly left the gun unattended and his son picked it up. ( ABC News )

Acting Inspector Goan said the incident was a "tragic reminder" that weapons needed proper storage.

"They are an otherwise law-abiding family," he said.

"If you have these types of weapons you have a responsibility to keep them properly stored and he has failed to do that, and as a result of his negligence the young girl has been seriously injured.

"It could have been quite catastrophic. Then that sibling would grow up knowing he had taken the life of a younger sibling.

"The impacts of what has actually occurred is devastating as it is. If you've got a gun, lock it up."