Why is it unsafe to leave engine running while pumping gas?

Question

I see signs stating to turn vehicle off while pumping gas into car. But I see cars filling up all the time while leaving the engine running?

Nothing so far has happened?

Why is it unsafe to leave the engine running while refilling the fuel tank on a vehicle?

Answer 1

It's supposed to have something to do with sparks that could be caused from static electricity.

I've always left mine running without problems.

Just don't reenter your car while refueling.