As much as I'd love my child and want to protect them. I just could not put leash on them like a dog.
Heck I don't even like leashing dogs. My dog walks around with me free without a leash.
Kids take off and run away from you but you have to be watching them as close as possible.
Most parents nowadays are watching there phones anymore while out with their children instead of watching their children.
Watch your children closely and do your best to never let them out of your sight and if they do start to take off immediately start chasing after them yourself no matter what you were/are doing.
Don't yell for your other kid or friend to get them, you go get them yourself.