Rape. Sexual harassment. Gun obsession. Get police involved?

Alex • I'm not rude, I'm honest 💋
Sorry this is so long but it's very serious and I don't know if I need to get the police involved or not. There is a guy who is now 20 and I'm only 15. He got fired from his work at an ice rink I skate at because he slapped my friend who is a girl in the face not jokingly. They were fighting and he hit her. Ever since he's been fired he's messaged me and is trying to get with me. I told him its not appropriate because I'm too young for him but he won't listen. Any time I don't answer for  for more then 5 minutes he messages me saying stuff like "I know you're getting my texts, don't ignore me". I told him if he didn't stop I was going to get an adult involved. He said if I did get an adult involved or try to that he was going to make me have sex with him. I'm extremely scared of him because if he had the guts to hit my friend, he would have the guts to do the same thing to me. We used to hug at the ice rink just as friends whenever I needed a hug if I wasn't happy about something an the day he got fired he texted me "you know how I always hugged you at the rink? It's cause you turn me on". Right after he sent that I didn't respond and my phone blew up with messages. One thing that scares me even more is he has an obsession with guns. He's showed me so many pictures of the guns he has lined up in his house. I'm terrified of him. I don't know what to do. I want to get the police involved so he'll stop but I'm scared he will hurt me or even someone else.