Three girls accused of attacking another teenager "like a pack of wild dogs" near Wollongong, south of Sydney, face a maximum of 25 years behind bars if found guilty of the "vicious" shopping centre assault.

Footage of the alleged attack uploaded on social media showed a 14-year-old girl being beaten and left convulsing on a bathroom floor.

The video shows three teenagers carrying out the alleged assault at Figtree Grove Shopping Centre last Friday.

The victim could be heard pleading with her attackers to stop before she was knocked unconscious.

Two 15-year-old girls and a 17-year-old girl were charged with several offences.

The most serious carries a maximum 25-year sentence.

Victim on ground 'defenceless' in alleged attack

Police documents tendered in Port Kembla Court House on Monday described the alleged attack as "vicious", and that officers had "no idea how the victim didn't sustain more serious injuries".

The documents alleged the 14-year-old victim met one of the girls at the shopping centre and spent the next 30–60 minutes walking around with her.

Police claim the girl told the victim she needed to charge her phone in a nearby bathroom.

When they entered the bathroom the two other girls jumped out.

Police allege the girl tried to escape but was blocked.

"She lay defenceless on the ground to the group who were attacking her like a pack of dogs," the police documents read.

The victim's mobile phone was also allegedly damaged during the attack, before the alleged offenders left the bathroom.

She was assisted by shopping centre security before emergency services were called.

Allegedly pushed onto train tracks

The girl sustained bruising and soft tissue damage to her body and face.

One of the teens was also charged with common assault over a second incident at Woonona Railway Station, north of Wollongong, earlier this year, in which she allegedly pushed the same victim onto the train tracks.

The girl's defence lawyer argued in court on Monday that she was suffering from "significant emotional issues" and had no prior convictions.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume.

The 15-year-old applied for bail, but it was refused.

The teenager sobbed throughout the proceedings.

The second 15-year-old did not apply for bail.

Both girls were charged with take/detain in company with intent to get advantage, occasion actual bodily harm, assault occasioning actual bodily harm in company of other(s), destroy or damage property, and common assault.

The 17-year-old will face a bail hearing on Tuesday morning.

She was charged with take/detain in company with intent to get advantage, occasion actual bodily harm, and assault occasioning actual bodily harm in company of other(s).