The truck, sporting outsized tyres and a powerful engine, surged off the track on Sunday after driving over a line of prop cars, crashing through a barricade in the street and into the audience in the eastern town of Haaksbergen.
"A serious accident occurred this afternoon at a motor show," the local municipality said in a statement.
It added that two people were killed, revising lower an earlier toll of three dead.
Eighteen other people were injured, six of them seriously, Dutch public broadcaster NOS reported, citing the mayor of Haaksbergen, Hans Gerritsen.
Several emergency helicopters, ambulances, fire trucks and police cars rushed to the scene, as well as rescue services from nearby Germany, Dutch state television said.
The driver of the "monster truck" has been detained and an inquiry has been opened into the incident, police said, according to local media.
