The two died at the Medical College Hospital in Kozhikode where they were admitted in a critical condition, they said.
Five workers were charred to death on the spot and seven injured when the unit at Panniankurissi caught fire and exploded with a deafening noise yesterday.
Police and explosive experts have begun a probe into the accident and questioned the person who holds the licence for the unit, which engaged the victims for making fireworks for temple festivals in Palakkad, Thrissur and Malappuram districts.
The state government had announced an interim solatium of Rs 10,000 each for the bereaved families. The district administration has ordered a preliminary inquiry by explosive experts.