If it would somehow protect my kids in the moment, I'd do it - despite not ever being willing to do it otherwise.
I remember my biggest "mama bear" moment. My younger son was in jr high. My husband casually told me that son and a friend of his were in a nearby city going to a concert but neglected to mention that his friend's mother was with them. The city is across the water from us. My first impression was that he'd somehow let them take public transportation and just go. If I had been closer to the water, I would have dived in and started swimming - whatever it took, period. I remember this HUGE adrenaline rush and a need to do whatever possible to protect him. It was so strong I don't know that anyone could have stopped me. It took me a while to calm down, the feeling was just so strong.
DH thought I was nuts, he would never have let them do that at that point nor would the other parents, but I was so panicked in the moment and the feeling was so strong that I wasn't thinking.