Three people have been injured in a workplace incident at a factory in Sydney's west.

It is believed one man in his 30s was crushed by pallets at a Woolworths factory on Sargents Road in Minchinbury this afternoon.

Two other men, one in their 30s and another in their 20s, went to help the man but were also injured.

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The first man is believed to be in a serious condition.

More to come.