A high power enquiry committee headed by senior space scientist R Aravamudan is currently at work at the ISRO launch centre at Sriharikota trying to find out what caused the fire accident there on Tuesday.
ISRO chairman G Madhavan Nair also rushed to the spot as soon as the tragedy occurred.
ISRO sources told rediff.com that the accident occurred on a segment of a test rocket motor at the Solid Propellant Space Booster Plant (SPROB) at Sriharikota.
It claimed the lives of six persons, including an engineer, three technicians and two helpers, and caused burn injuries to three persons. The crew of nine people was engaged in the cast-cure facility.
The committee is also assessing the extent of damage and the corrective actions required for the future.
As of now it is only known that the fire happened when a test propellant segment was being prepared for transportation after curing. The propellant in the segment caught fire, and caused severe damage to the building, in which the operations were going on.
"The work going on at the time of the fire accident was the final operation of removing the fixtures after the satisfactory conclusion of propellant curing of a segment of a motor holding around 14.5 tones of solid propellant, which is a composite of Ammomium Percholorate Oxidiser, with atomised aluminium powder as fuel and Hydroxy Terminated Polybutadiene as binder," said a senior ISRO scientist.
"Yesterday morning the crew had satisfactorily concluded the removal of mandrel, which is one of the critical operations. At around 3.15 pm the crew were attending to the removal of the bottom plate of the casting assembly. During these operations, the propellant in the segment inadvertently caught fire."
According to ISRO sources the men trapped and killed in the accident experienced the intense heat and fumes of the burning 14.5 tonnes of propellant.
Senior engineers Y Krishna Prasad and S Narayanan, and tradesman S K Sachin were the only three of the nine people working on the operation who managed to escape. They were immediately rushed to Apollo Hospital, Chennai.
Engineer Ramakrishna Prasad, senior technicians Basheer Saheb, N Krishnaiah and Srinivasulu, helpers Pandit and Sanjiv could not escape from the building and were asphyxiated, ISRO said.
The building suffered damage to the tune of Rs 7 million.