A female driver was hospitalised after being struck by a missile in Droylsden last month.
The woman was hit on the temple and left with a puncture wound by an unknown object thrown through her open offside window while driving along Edge Lane at 2:40pm on July 27.
Witnesses said that three youths were seen on the grassy verge on Bradford Garage overlooking the road, throwing missiles including eggs, stones and branches at passing traffic between 2pm and 2:45pm that day.
They were also seen placing large branches in the road, forcing motorists to swerve out of the way.
Detective Constable Sue Holt said: “The actions of these three youths were reckless, foolish and downright dangerous.
“They put the lives of numerous motorists at risk and even hit one woman, who needed hospital treatment to treat a wound to her head.
“It is thankful she did not suffer more serious injuries or lose total control of the car.
“These three individuals might have thought they were ‘having a bit of a laugh’ but I can assure you it was anything but and we are taking this matter extremely seriously.
“They put people in grave danger and we need to identify who they are.
“I would appeal to anyone who has information about what happened, or witnessed the missiles being thrown, or if you suspect who may be responsible, to come forward and speak to us.”
Anyone with information is asked to call police on 101 or the independent charity Crimestoppers, anonymously, on 0800 555 111.
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