A distraught mother whose two sons were caught up in a deadly youth brawl in Canning Vale has told how her children have been left traumatised by the violence. 

"They are hugely affected by this, worried, scared of repercussions and sad for the loss of life," she said. 

A teenage boy died and several people were seriously injured on Thursday after two violent incidents in Canning Vale involving a group of teenage boys. 

According to witnesses, two people were stabbed during a fight outside McDonald's at Livingston shopping centre around 3.15pm, with both found laying face down in bushes. 

Around an hour later a vehicle ploughed into a group of teenage boys on Eucalyptus Boulevard in Canning Vale - killing one boy, 17, and injuring several others.  

According to the mother, whose two children were present during the fighting, a group of youths from Belmont had travelled to Canning Vale to fight a student from Canning Vale College in a park. 

Video of the fight - which WAtoday has viewed - showed two young males, one in a Canning Vale College uniform, punching each other as a group of students watched on and filmed the incident on their mobile phones. 

In the footage, a person can be heard egging one of the males on as the pair wrestled.

After the fight, the group then moved on to McDonald's. 

"[The Belmont group] randomly hit kids and tormented them, stealing bikes," the mother said.

"[A Canning Vale College] kid got hit in the eye, he got his family down to help him get his bike back. 

"One of his sisters got stabbed in the arm and a [Belmont group member] also got stabbed supposedly by accident by one of his own gang."

The mother alleged the woman who was driving the car that mowed down several teenagers was the sister of the girl stabbed at McDonald's. 

"My boys could see the potential for violence and left encouraging all their friends to do the same," she said.

"They felt helpless to help their buddies as they would be mobbed by the gang.

"Gang violence has escalated in this area, kids having issues with other kids over petty things, it has led to a death now."

Police are yet to confirm the details of the incident. 

Seven people were taken to hospital as a result of the encounters.

Two 16-year-olds and a 17-year-old are in a critical but stable condition at Royal Perth Hospital.

Two others were taken to Fiona Stanley Hospital but their condition was unknown, with staff at the hospital directing media to police, while another two people were discharged from Armadale Hospital with minor injuries on Thursday night. 

Another witness who lived on Eucalyptus Boulevard told Nine News Perth she rushed outside her home after hearing a crash, to find people scattered across the street. 

"There was a big accident right in front of our house so all of us we get out from the house... first of all we've seen the casualty next to the red car.. and then the next one just few metres away.. there's another four you know it's just scattered," she said. 

Homicide detectives are investigating the incident with one adult, reportedly a young woman who was driving the vehicle, in custody assisting police with their enquiries.

The Department of Education has sent a student services team to Canning Vale College on Friday morning to support students. 

- with Daile Cross