Officers were called out at 1.43am on Thursday to Craven Arms after it was reported a girl had been attacked while walking through an alley near the town’s railway station.
Police believe the offence happened about midnight after the victim got off a train.
Officers are carrying out inquiries within the area and a scene guard is in place while the investigation is ongoing.
Dafydd Jones, Shrewsbury Detective Inspector, said there are a ‘significant number’ of officers dedicated to the investigation.
He said: “We understand incidents such as this are extremely concerning to the community and we would like to reassure the public that we are following every line of enquiry and that there will be an increased number of patrols in the area while the investigation continues.
"Please be assured there are a significant number of officers dedicated to this investigation and the scene guard will be in place overnight while they carry out searches and make their enquiries.”
Anyone with information is urged to call 101 quoting reference 024i of April 15, or alternatively report it online through the Tell Us About section of West Mercia Police website.
Alternatively, contact Crimestoppers anonymously on 0800 555111 or at crimestoppers-uk.org