Closed printing plant/paper mill has been the target of vandals in recent years.
Anhydrous ammonia presents a risk of explosion under the right circumstances.
Previous blast occured at plant in December.
Fire chief says plastic wall covering helped fuel the flames.
A structure fire further stretched Saint John Fire Department resources thin.
Six-hour operation suspended to prevent runoff from polluting nearby river
Localized corrosion in hydrogen desulfurization unit blamed for explosion that injured 80
Flames broke out in cutting fluids used at the plant
When 22 tons of pool cleaning tablets began to oxidize in a shipping container, acrid fumes created a toxic cloud.
Railroads have been operating under 30-day speed restrictions in the wake of Feb. 6 accident in Saskatchewan.