Two teenage girls and a man in his 20s have been killed after the car they were in hit a tree near Dudley in the West Midlands.
They were among five people in a yellow Skoda Fabia which crashed in Bromley Lane, Kingswinford, at around 8.50pm on Tuesday.
An air ambulance, a critical care vehicle, three paramedics, an emergency doctor and six ambulances were sent to the scene.
A teenage boy and a teenage girl are in a critical condition in the Queen Elizabeth Hospital in Birmingham.
The man, who was driving, and the two girls, who were sat in the back, were pronounced dead at the scene, West Midlands Police said.
The force said officers had seen the vehicle moments before the crash, but did not speak to the occupants or pursue it.
The families of all those involved have been informed.
Confirming that the road had reopened after being closed overnight, Sergeant Dean Caswell said the inquiry was at an early stage.
He said: "This is a tragic time for the families of those involved, and we have specially trained officers who will be supporting them through the difficult time ahead.
"I'd urge anyone who saw the Skoda driving in the area last night, or who may have captured anything on dash-cam footage, to get in touch with us as soon as possible."
A West Midlands Ambulance Service spokeswoman said: "Crews arrived at the scene to find a car had hit a tree, with five patients involved.
"Sadly, it soon became clear nothing could be done to save the driver of the car, a man, and he was pronounced dead at the scene.
"Despite best efforts of staff, two teenage girls who were back seat passengers in the vehicle were also confirmed deceased at the scene.
"Our thoughts go out to the families of all those involved at this time."
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