Two men are in custody after police in an alleged 'kill car' in Sydney's west with a shotgun, jerry cans of fuel and sledgehammers.

Police allege the pair were planning a violent crime, after also finding baseball bats, duct tape, cable ties and pillowcases in the car.

Investigations began at 2.40am yesterday after police were called to a home invasion at Karangi Road in Whalan, where they were told four men forced entry into the house, allegedly with a gun and hammer.

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The men left in a black Mercedes SUV before police arrived.

Later yesterday, police saw two men in the garage of a home on Issanthe Street, unloading items from a Mercedes SUV into a Hyundai hatchback.

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When the hatchback left the house, it was stopped by police.

The two men were arrested, and a search was undertaken on the Marsden Park home by Raptor Squad, where the black Mercedes was allegedly seized.

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Both men, 22, were charged with multiple offences, including possessing unauthorised firearm[s].

They were both refused bail to appear at Mount Druitt Local Court today.

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