Four men have been killed after the car they were travelling in crashed into a tree.
Police said they came across the crash on the A436 in Ullenwood, near Cheltenham, while on patrol shortly after 02:00 BST.
Those who died were found inside a black Renault Clio, Gloucestershire Police said.
A force spokesperson said urgent work was ongoing to identify all those involved, who are aged 18 or over, and notify their next of kin.
The road was closed in both directions between the A417 Air Balloon roundabout and Seven Springs. It has since reopened.
Anyone who has any information about the crash, or has any dashcam footage, has been asked to contact police.
Gloucestershire County Councillor for the area, Paul Hodgkinson, said there had previously been fatal crashes on the “exceptionally busy” road and accidents were “a regular occurrence”.
He said: “It’s terrible, I was just horrified that four people have lost their lives and my heart goes out to their families, it really does.”
He said he had been calling for improvements on the road “for ages”, adding that residents felt “unsafe”.
A Gloucestershire County Council representative said: “Our thoughts go out to the families and friends of those lost.
“It would be wrong to jump to any conclusions during an ongoing investigation.
“As with any incident of this kind we will conduct a review along with other agencies and take the necessary action where needed.”
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