Went to save a lost dog. Didn’t get there fast enough. Got hit. Watched it die

A few hours ago I was driving home and a little French bulldog on a leash ran in front of my car. It looked so scared. I braked and watched it run out into an intersection and I was going to pull over to go run out and save it so it didn’t get hit but I figured it would be faster and more efficient to do a u-turn at the next light so I’d be on the same side of the road. There was also a cop behind me that pulled over and I assumed they noticed and were going to help it. By the time I did the u-turn and got back to the intersection (which was no less than a minute) I was shocked to find that all the cars were gone and the dog was twitching in a pool of blood in the middle of the intersection. Someone had just hit it and left. I pulled over and I was wondering why I wasn’t reacting then I just started hysterically crying and freaking out and I just sat there waiting for it to move again for like fifteen minutes and it never did. So many thoughts are going through my head and I can’t sleep at all. I feel like I should have got there faster. I also called 911 way too late I was just so sure it was dead but maybe it was alive and they could have saved it?? I can’t stop thinking about the leash and the poor owner that was probably wondering where their dog went. I feel like I could have done more this is really messing me up I just wanted to say this somewhere.