Welding sparks may have started a fire in Stone Container's old Kamyr digester tower.
Frenchtown firefighters responded to smoke rising from the skyrocketing landmark late this afternoon.
Firefighters could be seen climbing stairs to the huge structure.
Fire department spokeswoman Patty Dreiling said the fire appears to be minor.
"Welders had been in there." she said, "They're taking the buildings down."
An ambulance was sent as a precaution. Dreiling said there were no injuries.