Intensive Care Paramedic here. Crush injury is a risk, but usually after more prologned entrapped, without blood supply to the affected area. Usually >45mins - but sometimes less. We carry drugs to counter the effect of the sudden release of toxins that damage the heart.

What is more risky here is not the release of the vicitim - but the potential for a failed release. What if 100 people tried to lift the bus, but it turns out they wernt strong enough, resulting in the bus just pivoting on the spot. That pivoting might have crushed the injury further - leading to significant more damage. When we extricate patients - we always aim to do it in a controlled environment. Even when they are sick, slow and steady is often best.

One of the worse worse worse things bystanders often do is pull objects out of patients. i.e. if you are stabbed, and the knife is still in you - do not pull it out.

I think bystanders think they need to do "something" - but sometimes doing nothing (i.e. dont pull the knife out) is best.