Two teenage girls have been charged after a teenage girl was allegedly stabbed during a brawl in Sydney’s west.

About 2.30pm on Friday, emergency services responded to reports of a brawl outside Blacktown West Public School on Lancaster Street.

The 17-year-old girl was stabbed multiple times before running onto the grounds of the primary school for help.

Paramedics treated the teenager for multiple stab wounds before taking her to Westmead Hospital, where she remains in a serious condition.

The girl is not believed to be affiliated with the school which goes from kindergarten to year six.

The alleged brawl involved around six people, who fled the scene before emergency services arrived.

Police at the scene. Photo: 7NEWS

Two girls – aged 15 and 17 – were arrested at Mount Druitt Police Station.

Police conducted a search of a vehicle allegedly used during the incident and allegedly located and seized a knife.

The 17-year-old was charged with wounding a person with intent to cause grievous bodily harm and affray. She was refused bail to appear before a children’s court on Saturday.

The 15-year-old girl was charged with affray and granted conditional bail to appear before a children’s court on 14 September.

Officers have established a crime scene and investigations have commenced into the circumstances of the incident.

Anyone who witnessed the brawl or has relevant dashcam or mobile phone footage has been urged to contact Blacktown Police Station or Crime Stoppers.