Four men armed with a firearm and wearing balaclavas have forced their way into a home in Sydney's southwest.

They entered the home on Neville Street, Yagoona, about 3.15am (AEDT) on Tuesday and threatened the two men and a woman inside.

The thieves demanded cash and stole personal belongings before running from the home.

No one was injured during the incident, police said.

A crime scene has been established while specialist police carry out their investigations.