Bystander effect scary! A guy collapsed on a crowded street, and for some reason it formed an area around him where no one was. We checked on him and called an ambulance, and only after that someone called a local first aider (aka staff of the train station nearby, with a first aid kit and an extra special training).
First seconds and minutes matter in an emergency. Don't be a bystander. Get that first aid certification you always wanted but never had time and energy to complete. If nothing else, at least read up on riot medicine and stay alert.
https://riotmedicine.net/downloads#basic-first-aid-for-emergencies