Two teenagers have reportedly been stabbed and another injured after gatecrashers invaded a party at a home in Sydney's west.

Police called to the Northmead house about 10.45pm on Saturday found a 17-year-old boy and a 19-year-old man with wounds to their back and an 18-year-old man with a hand injury.

The trio were taken to Westmead Hospital in a stable condition. Their injuries are not considered life threatening.

Officers were told an argument had taken place after a group gatecrashed the party.