Policeman hurt, two stabbed in Sydney brawl

A NSW policeman has suffered minor injuries during a brawl in which a father and son were stabbed.

The sergeant was hurt when a crowd of onlookers confronted police during the brawl at Guildford, in Sydney's west, shortly before 5.30pm on Sunday.

The father and son, aged 42 and 21, were taken to Westmead Hospital with injuries that aren't believed to be life threatening.

A third man, aged 21, was arrested at the scene and is assisting police.