The crash happened about 6am on Pages Rd, Wainoni, Christchurch.
A Pages Rd resident said the car was speeding and trying to "drift" before crashing into a power pole.
The resident, who ran outside when they heard the crash, said one of the car's back wheels "went flying" 15 metres down the road due to the impact of the crash.
He said two of the occupants had already fled, while the third occupant told him they were fine and to go away before leaving the critically injured girl alone.
The witness said he rang the ambulance.
He believed the four occupants of the car were all aged 15 to 18 years old.