Fire service personnel and other staff put down flames in the generator room in the Sutherland Global Services compound, Velachery.
The massive structure sits by a very narrow bottleneck in Velachery. The fire and the ensuing commotion jammed traffic for over an hour.
A stray spark from the generator hit a tank with over 500 litres of diesel a little after noon on Thursday. An alarm was sounded and the building cleared.
Closer inspection by the Fire Department revealed that the installation itself was illegal. The structure left no space for fire tenders to approach the source of fire.
The fire was extinguished within an hour, but the safety concerns it raises will cloud the employees and the government's enforcement agencies for sometime yet.