Hm, that is rather worrying. =/ Especially since your mum received the same message. Did any of your friends get it also? Have you heard about this actually happening? It is strange, but it could be true. Perhaps you should go to the police just to be safe. This could be definitely true and actually happening and in that case, anyone could be a target of these people who are doing this. I think you should just be very careful around that area, don't go there alone but also go to the police about this. Report this message you have received. Good luck and be safe! :)