A 13-year-old girl who fought off an attempted rape was on her way to school when the attack happened, police have said.
The teenager was sexually assaulted in Nunnery Wood in Worcester at about 08:15 GMT on Tuesday before fleeing and seeking help from a member of the public.
The suspect is described as mixed race or Asian and between 16 and 18 years of age, West Mercia Police said.
Nearby Nunnery Wood High School has urged students to walk and cycle with others, while Worcester Sixth Form College has warned students to "take sensible precautions".
Ch Insp Dan Pilkington, from the force, said it was thought the suspect followed the girl "for a short time through the woods before he forced her into the trees".
"We now know that the victim was a 13-year-old schoolgirl on her way to school that morning," he said.
Officers have made house-to-house inquiries and are working through "several reports of information" made following an appeal on Tuesday.
Pilkington said the force was looking for a male seen wearing all-dark clothing and it was not believed the girl knew her attacker.
"The victim in this investigation remains our priority and is being supported by specially trained officers as we work to find the person responsible."
'Remain aware of surroundings'
The girl was walking along a footpath through the woods between the hospital and Nunnery Wood High School prior to the assault.
Pilkington said the "woods remain a safe place to be" and there would be a visible police presence in the area, especially at school times.
"If you can avoid walking, particularly alone, during the hours of darkness or take main arterial routes, ie, not cut through the woods at those times, that would be the best advice that I can give," he added.
In a letter to parents and carers, the high school said it would speak to students "about the incident and guidance about getting home".
"They will be told to avoid the Nunnery Wood area, to stay on residential roads and to walk [or] cycle with others," it added.
The college encouraged students to walk with friends where possible, stay on well-lit routes and report any suspicious behaviour to staff or police.
"Whilst we do not wish students to be alarmed, we feel it is important to reinforce good personal safety habits and encourage everyone to remain aware of their surroundings," it added.
Bus companies have been urged to contact police with dashcam footage from the area near Worcestershire Royal Hospital car park.
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