A man has been charged with firearms offences after a joint NSW Police, US Homeland Security and Border Force raid found a loaded pistol in a house with children inside.
The 36-year-old also faces international drugs charges, after the raid on a granny flat in Bathurst, in regional NSW.
Teams from multiple agencies searched the home on Violet and Prospect Streets, and a specialist Hazmat unit was called in after police said a "suspicious substance" was found inside.
The 36-year-old male resident was served with firearms and weapons prohibition orders before being arrested and taken to Bathurst Police Station (Supplied)
The alleged substance was around one litre of an unspecified drug-related chemical, police said, which began to mysteriously crystallise during the search.
Police allege two young children were also at the house, where a loaded .45 calibre handgun was seized. Family and Community Services have been informed.
Both homes either side of the property were evacuated, and a 50-metre exclusion zone was set up.
Police say he'll likely to face more charges.
Last month police received information over the alleged importation of firearm parts and drug manufacturing equipment into Australia from the US, Hong Kong, China, Germany and Japan.
Those items allegedly included trigger mechanisms and gun barrels.
The ABF alleged at least 10 importations had been tracked coming into Australia.
Bathurst police commander Peter O'Brien said information had initially been flagged up by "various intelligence sources" around the world.
NSW Police footage of the raid showed authorities speaking to the arrested man.
Australian Border Force Inspector Tony Wheatley did not rule out the suspect and raid could be connected to a wider criminal syndicate.
"The bulk of the imports have come through air cargo or our international mail stream," he alleged.
The investigation, which began in August, was conducted by NSW Police in tandem with Australian Border Force and US Homeland Security.
Inspector Wheatley called it a "fantastic example" of joint agency work.
"This goes to show the power of a global focus on illegal firearms."
NSW Police Detective Inspector Rob Bevern, with Western Region Enforcement Squad, said a hazmat unit was called soon after police executed a warrant.
"Officers located a suspicious liquid in a container that had started to crystallise."
Specialist officers from the Rescue and Bomb Disposal Unit and the Drug and Firearms Squad's Chemical Operations Unit were called out to examine the substance.
Detective Inspector Bevern said it was "not unusual" for US agencies to in Australia and be part of the raid.
"Today's action demonstrates how agencies at a state, federal and international level work collaboratively to detect and disrupt criminal activity," Det Insp Bevern said.
"Firearms can cause considerable fear – we know that when in the wrong hands, they are dangerous and a serious threat to the safety of our community.
"This investigation should send a clear message that no matter where you are, if you are involved in criminal activity, law enforcement agencies will do everything in their power to ensure you are brought to justice."
The man was served with firearms and weapons prohibition orders before he was arrested and taken to Bathurst Police Station, where he was charged this afternoon.
The man was refused bail to appear at Lithgow Local Court tomorrow.