Three workmen have escaped through a bathroom window after allegedly being threatened by a resident armed with a handgun.

The incident unfolded at a property in Sydney's southwest about 11am on Thursday, police said.

Officers established a perimeter outside the Condell Park home with assistance from the Public Order and Riot Squad, the Tactical Operations Unit and PolAir.

After a three-hour standoff, the 44-year-old resident was arrested and charged with a slew of firearm, drugs and assault offences.

The changes include firing an unregistered firearm, stalking or intimidating with the intention to cause fear or physical harm and taking a person with the intention of committing a serious indictable offence.

The man has been refused bail and is due to appear before Bankstown Local Court on Friday.