The fire brigade in the next town up from us had a callout to a runaway diesel train engine at the yard last month! Nothing would stop it but the engineer finally stuffed jackets and garbage bags in the air intake...it stopped.
Everyone was very happy, things were getting very, very hot!
Yep, simply choke it to death.
That is the easiest way to deal with that.
Plastic bag over the intake.
That works great with noisy kids, too.