A raid on a supposed safe house has allegedly uncovered a haul of drugs and weapons including assault rifles and grenades.

NSW Police, with assistance from the Raptor Squad, executed a search warrant at the home in Glenfield, southwest Sydney, about 9am on Tuesday.

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Officers allegedly located and seized a number of weapons, including six grenades, three semi-automatic assault rifles, four shotguns, a pistol, firearm parts and more than 1000 rounds of ammunition.

Drugs including 6kg of cocaine, 1kg each of methylamphetamine and ketamine, 1.1kg of heroin, 15kg of cannabis and 106g of MDMA were also allegedly found at the home alongside electronic devices and about $9000 in cash.

Police allege the drugs would have an estimated street value of up to $3 million.

A man and a woman, both aged 26, were arrested and taken to Campbelltown Police Station soon afterward.

The man was charged with 27 weapons, drugs and organised crime offences.

He was refused bail and is expected to appear before Campbelltown Local Court on Wednesday.

His alleged female counterpart was charged with a single count of organise, conduct, or assist in a drug premises and was granted condition bail. She will appear before the same court on August 27.

A raid on a Sydney property has allegedly uncovered numerous firearms, grenades and about $3 million worth of drugs. Credit: NSW Police

Grenades same as those used by military

Assistant Police Commissioner Scott Cook said the discovery of the grenades was of particular concern to investigators as it is “significantly different” than weapons found during previous raids.

He confirmed the explosives appear to be the same as those used by the Australian Defence Force or the US Military, which is now a line of inquiry for police.

While the grenades appear to have been stored in a way that kept them from randomly detonating, Cook said the result would have been devastating if they had exploded.

“The damage that they could cause is entirely indiscriminate,” Cook said.

“If they were to be set off altogether, I imagine they would probably almost demolish the building.”

Police and Counter-terrorism Minister Yasmin Caitles said it’s “awful to think what could have happened if police hadn’t intervened when they did”.

“We do not want to see these weapons in our communities and thanks to the hard work of police, they are now out of the hands of (alleged) criminals.

“To anyone thinking of taking part in this alleged vicious criminality, our message is be prepared to spend a long time in a small cell.”

A man and woman, both aged 26, were arrested and remain before the courts. Credit: 7NEWS

One of three raids

The raids were the second of three raids conducted under Taskforce Falcon, established to target organised crime networks in Sydney, on Tuesday morning.

The first was at a home on Marsh Pd in Casula about 8.10am, which allegedly uncovered a pill press and a clandestine lab allegedly used to manufacture steroids.

Police also allegedly located compound bows, gel blasters, knuckle dusters, a laser pointer and a baton at the home.

A 40-year-old man was arrested and charged with weapons offences, and single counts of possessing tablet press or drug encapsulator and dealing with the proceeds of crime.

Officers then raided a home on Ives Avenue in Liverpool about 9.30am and allegedly seized “a rifle and pistol ammunition, 550g of cocaine, electronic devices $5000 in cash and $20,000 in counterfeit cash”.

A 31-year-old man was charged with weapons offences, dealing with the proceeds of crime and allegedly knowingly expose a child to drugs.

Both men were refused bail and will appear before court on Wednesday.

Assistant Police Commissioner Scott Cook said that if set off, the grenades could have had enough power to demolish the alleged safe house. Credit: 7NEWS

Concerning trend going global

Police will allege all four accused are “contract criminals” without any specific ties to crime groups and are instead “engaged in criminal activity for the purpose of profit”.

Cook alleged they’re part of a trend growing not only in NSW but also spreading overseas.

“We’re seeing far more contract criminals who are being tasked and providing services to a larger serious and organised crime network that’s operating not just in New South Wales, but now globally,” he said.

“They’re operating under their own steam and they’re committing offences under their own steam, providing services to others.”

He said police will continue attempts to disrupt organised crime networks, and issued a warning to active criminals.

“People who engage with serious and organised crime or enable or facilitate that crime need to understand that we will not ease up on you,” Cook said.

“We will keep coming for you, whether you are in NSW, Australia, or abroad.

“We will not give up. The violence has to stop.”