Firefighters needed less than 90 minutes to extinguish the blaze.
No injuries were immediately reported in the two-alarm fire, which began at the complex at Market and River streets around 7:45 p.m.
The crane, which operates on a long track, ran over the cord, igniting a spark that lit the paper dust bowl in Building 10, said Police Chief Michael Foligno, who is also the borough administrator.
Firefighters accessed the flame with a ladder truck and an inside stairway, knocking the fire down in under an hour. It was completely out less than 15 minutes later.
Joining their Elmwood Park colleagues were firefighters from Fair Lawn, Garfield, Lodi, Saddle Brook and Clifton.
Fires at the plant in 2017 and 2012 took hours to be doused.
VIDEO (above) by Mark Rosetti. For more of his videos, go to: DemonRacer2.
Click here to follow Daily Voice Saddle Brook-Elmwood Park and receive free news updates.