Polish border guards have found the remains of three Chechen girls aged 13, 10 and 6 in Poland's Bieszczady mountains, the apparent victims of an attempt to cross illegally from Ukraine into Poland, Poland's TVN24 hour news channel reported Friday, according to DPA. Border guards were lead to the childrens' remains by their mother, a 36-year-old Chechen national who had early been taken into custody with a two-year-old baby. Suffering from exhaustion, the woman and her baby were hospitalised in Ustrzyki Gorne, a small town at the foot of the Bieszczady range in south-eastern Poland. Border guards said weather conditions in the area of the high Bieszczady where the children were found made their survival difficult. They are believed to have died from exposure. Autopsies are to determine exact cause of death. Polish state prosecutors have launched an investigation into the case, but are not optimistic they will find people smugglers responsible for the tragic illegal border crossing. The mother of the dead children will be questioned as soon as her health allows, Prosecutor Zygmunt Slabik told TVN24. The woman and her children had been lost in the Bieszczady mountains for four days.