It might have scared him off temporarily, but chances are in a few days he's going to think he has calmed down. That's when he will reach out to you about some innane bullshit. Something related to his case or some other thing that you two shared that he could claim made it necessary to contact you. If you don't respond, he'll revert back to sending a barrage of messages. If you respond at all, he'll take it as an opportunity to continue talking.
If you want to call the police, do so. You deserve to feel safe and should have no qualms about making the call. If you think he's just the type of person who does stupid shit after a break up and don't want to go that far, here are a couple of suggestions:
Call your cell phone carrier and pay them them small fee to block his number. When he calls or texts you, it will tell him that he has been blocked. The phone harrassment by exes is often times just a coping mechanism. When they are made aware that the avenue no longer exists, it can snap them out of it.
Don't block him, but the next time he contacts you tell him that you're worried about his mental health. If you know a family member or good friend of his, call that person and explain the situation. Offer to show them the messages. They might be able to slap some sense into him.
If you don't know anyone like that, tell him you think he needs the help of someone else and that if he continues, you'll call his employer and raise your concerns.
I had the unfortunate experience of dealing with an ex-girlfriend that behaved similarly. When I suspected that she might have vandalized some of my property, I considered calling the police, but decided to use the routes above instead.
I'm 6'2" 200 pounds, so I never felt threatened. Please know I am fully aware that your situation presents a real threat and the police are most likely the safest, smartest option. Just wanted to offer some advice in case you didn't want to go that route. Be safe. Good luck to you