More than 24 hours after the wax hydrofinishing plant of the Digboi Refinery went ablaze nobody is sure as to how the mishap occurred. At around quarter past eleven yesterday morning, the entire Digboi township was jolted by a large explosion . Before the terror struck population of the town could blink, about 50 persons have been injured, two of them critically, both of whom are under intensive care at the ultra modern AOD hospital.