Police say speed played a part in the death of three teenagers when a BMW hit a tree at a Perth intersection.
Two youths and a girl, all aged 17, died after their sedan slammed into a tree as they passed the High Street intersection on Vahland Avenue in the southeastern suburb of Riverton around 9pm (WST).
A female passenger, also 17, is in a serious condition in the Sir Charles Gardiner Hospital with head and internal injuries.
"It appears speed was a contributing factor," police spokesman Ian Hasleby said.
He said there was a 70km/h speed limit in the area.
Police say the BMW slid sideways and crashed into a large tree on the median strip after passing the intersection, which is controlled by traffic lights.