What would you do about this situation?

I have seen the same guy at the same park two times already. One time I was watching the guy as he sit across from me and my grand baby while she was playing in the park. Well this guy acted suspicious and it bothered me at the time. Since he was sitting across from me at the park I noticed him of course. I thought he was acting strange. But I didn't want to make anything of it. But then like twenty minutes later I hear a fire truck come flying up to the park. Someone in the park had obviously set a fire or dropped a cigarette and it started a fire so the foreman had to come and put the fire out. I walked over and looked, left the scene and didn't tell the fireman about the strange man in the park due to the fact I didn't see him start a fire or anything. He was just acting strange to me that day. Ok another day me and my grand baby are in the park again. Well this time the same guy is on a bicycle. As I was watching my grand baby play in the park then this same guy comes out of no where and is on a bicycle and rides almost up to my grand baby and almost hits her. He missed her but scared her so bad that she started screaming. I ran to her and held her to calm her down. You could still see the marks on the concrete where this guy slid and missed my grand baby before he rode out of the park really fast on his bike. I had no time to say anything to him about the bike incident. I am concerned that this guy has a problem and I'm not sure why he seems to be addressing it toward me and my grand baby. Another thing happened as well someone tried to steal one of my daughters bikes she had on her front porch like literally a day before the bike incident. Would you be concerned or not. I have decided to call the police if he ever gets near my granddaughter again with his bicycle. I just don't know if the police want to be bothered with such little incidents. Although I don't want to take any chances with this person because he seems to have my attention now and it's not good when he messed with my Grand baby! Thanks for your answers!