Police launched a murder investigation into the death of a little boy after a distraught passer-by stumbled on his body at a cottage in a picturesque Oxfordshire market town.The primary school age child was found at an address in Faringdon on Tuesday lunchtime.Paramedics were quickly on the scene but were unable to revive the boy.Shortly after police arrested a 40-year-old woman on suspicion of murder and sealed off the row of terraced cottages where the child was found.Thames Valley police confirmed a murder investigation was under way and increased their uniformed presence in the area in order “to provide reassurance”.The child’s body was taken to the mortuary at the John Radcliffe Hospital in Oxford, where a post mortem examination was to be carried out to establish what had caused the child’s death and whether he had been attacked with a weapon.Forensic science experts spent much of Wednesday combing the £250,000 terraced cottage for evidence. Detective Inspector Dave Hubbard, senior investigating officer with Thames Valley Major Crime Unit, said: “Following the discovery of a deceased child, we have launched a murder investigation.”The next of kin have been informed and we are offering support to them. We are in the very early stages of this investigation and an arrest has been made in connection with this incident.”No motive for the murder was believed to have yet been established and police refused to confirm whether a weapon had been used in the murder.Police declined to say whether the death was being treated as a domestic incident or whether anyone else was being sought over the killing. Forensics officers at the house where a child was found deadCredit:Peter Macdiarmid/London News Pictures The child was believed to have been a pupil at nearby Ferndale House Preparatory School before it closed down last summer and is thought to have moved to the local infants school, where staff and pupils were understood to be in shock.Local welfare services were understood to be liaising with police over the killing.As news of the child’s death spread through the town locals began to leave bunches of flowers and cards at the scene. One of the cards read: “RIP young man.”One woman walking to school with her son stopped to give a rose to one of the police officers monitoring the cordon placed around the cottages where body was found.Karen Draper, a local resident, said: “News like this is just devastating to a community and will have a resounding effect for a long time to come. “Candice McArthur, 44, said: “It’s a terrible tragedy not just for the little man but for the whole wide family. These things can happen anywhere, but you never expect it to happen on your back doorstep in a small little market town like this.”Everybody I know feels shocked and just disbelief together with a huge sense of sadness.”LPA Commander for South and Vale of White Horse, Supt Rory Freeman, said: “This is a very shocking discovery and I am aware it may have a very direct impact on the community of Faringdon.“In light of this incident there will be an increased police presence in the area to provide reassurance and we would advise any members of the community affected by this incident to speak to one of the Neighbourhood Policing Team.” TVP has launched a murder investigation in Faringdon. Sadly a young child has died. We have made an arrest. https://t.co/ug42nAwoEF— Thames Valley Police (@ThamesVP) March 14, 2017 Police urged anyone with information to call 101, quoting reference 730 (14/03) or contact Crimestoppers anonymously on 0800 555 111. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.