Most of the workers killed in a grain elevator explosion in Kansas were men younger than 25, reflective of what experts say in the norm in an industry that involves a lot of physical labor and tends to be dangerous.

Farmers take their grain to elevators to be stored and sometimes processed before it’s marketed or sold. Highly combustible grain particles flow through the buildings as grain is moved, and a mere spark can ignite the dust.

Six people died and two others were seriously injured in the blast Saturday at the Bartlett Grain Co. elevator in Atchison, northwest of Kansas City. Unstable concrete and steel inside the facility prevented crews from finding three of those killed until Monday.

The cause of the blast remains under investigation.