When I was seven, OP. My father was taking my sister and me to school, or he was supposed to. He was feeling sick that morning and my mother gave him some tylenol and left. Well, I get my little sister into the car and wait for my dad to come out.
Well, he walks out onto the driveway and stops at his door. I'm in front of him, looking at him, and he has this sort of confused look on his face. I call out to him and he just falls backwards like a board. Could hear his head hit the pavement. I run over to his side and I'm making noise and starting to cry. His eyes are really glassy and he keeps looking past me and not focusing. He's mumbling to himself and keeps telling me I need to get into the car, over and over. His eyes sort of flitter and he's not really moving, and I'm just sitting next to him crying. My sister is too little to get what is happening, so she starts laughing, thinking it's a game. I remember yelling at her to stop, but she just laughs more. Blood and some other fluid start coming from his head, and I just don't know what to do. A few cars drive past, but I doubt any of them really see us. One eventually slows down, reverses a bit, then some people come running over. Ambulance shows up and I'm taken inside by a fireman. Questions, calms me down. I stay at an uncle's for a few days.
The day I get home is the day they're doing this sort of... I dunno, goodbye party. No one told me he was dead, so I run in and ask my mom where he is, and everyone nearby gets quiet and awkward. Mom kneels down and says the doctors tried their best and gave him the best medicine.. and I just sorta say "oh", and walk to my room. Obviously I cried a lot, when no one could see me.
Turns out he had a massive heart attack, then a concussion. The first ten minutes after a heart attack are crucial, and I spent them all crying next to him. Not much else to say.