TeenHelp - My Friend is Threatening My School

Hi, this is very urgent.

I will not explain the backstory of my friend again, but he has complex PTSD, schizophrenia, very mild DID, he is being abused, etc. He just made a rap about shooting up a school and I asked him if it is personal in any way. His response: "Not really." The rap, however, has details about his life in it. He told me he used to think about shooting up the school and I asked him to swear on my life that he will never. He told me that he doesn't have any plans but if his schizophrenia takes over he might, and he said he is getting minimal help. This sounds very humorous but it alarms me as well; he said he is buying a TRENCH COAT to wear on the last day of school. I am terrified of him because he is very capable of getting a hold of weapons as his parents are very dangerous people. Please reply to this as soon as possible--the rest of my friends take this whole thing as a joke but I am not so sure. Thank you.