Police have charged two teenage girls after an alleged brawl outside a school ended with a girl being stabbed.

It’s alleged the fight broke out about 2.30pm on Friday outside Blacktown West Public School in Western Sydney.

A 17-year-old girl was allegedly stabbed during the chaos and walked into the school, which she has no affiliation with, in search of medical help.

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Paramedics arrived soon after and treated the girl for “multiple stab wounds” before rushing her to hospital in a serious condition.

All other people allegedly involved in the brawl fled the scene before police arrived.

Two girls have been charged after teenager was allegedly stabbed during a brawl outside of a school in Western Sydney. Credit: 7NEWS

Officers were seen outside of the school taking images of a footpath as part of ongoing investigations.

Police seized a knife during a search of a car they believe was used during the incident.

Two girls, aged 15 and 17, were arrested at Mount Druitt Police Station later that day.

The 17-year-old girl allegedly suffered ‘multiple stab wounds’ and walked into Blacktown West Public School to get medical help. Credit: 7NEWS

Both were charged with affray, while the older was also charged with wounding a person with intent to cause grievous bodily harm.

She will appear before a children’s court on Saturday while the younger was granted bail and will front court on September 14.