A police officer accidentally fired a Bushmaster rifle inside a police station, sending a bullet 8 metres as a colleague stood nearby.
A police spokesman confirmed the officer was in the middle of firearms training when the round accidentally fired from the M4 semi automatic rifle.
However, where in the country the incident happened remains unknown as police want to protect the officer's identity.
The spokesman said the training exercise was being carried out in February 2018 when the shot was fired.
One other officer was in the vicinity at the time.
The bullet travelled approximately 8 metres.
"The officer was subject to an employment investigation and a disciplinary process, however like any employer we are unable to discuss the outcomes of employment matters."
The Independent Police Conduct Authority, which oversaw the internal investigation, said the bullet went through an internal wall into an office and embedded itself in an external wall.
After it was determined that the officer's actions did not meet the threshold for a criminal prosecution, police carried out an employment investigation, the IPCA wrote.
"It was found that the officer's actions did amount to misconduct and he was dealt with through a confidential employment process. The authority agrees with the outcome."
A police spokesman said there are "strict processes around managing firearms which police staff follow every time they deploy with firearms".
"This was a rare occasion where there was human error and it was dealt with promptly and appropriately."
When officers use firearms outside an official capacity they are subject to the same rules and regulations as other firearms users.
"Officers are not able to use their police-issued firearms in an unofficial capacity."