Police are investigating the cause of the fire in a chemical laboratory at India's main nuclear research facility that killed at least two people.
A spokesman for the lab near Mumbai says the fire was extinguished quickly and that no nuclear reactor, radioactivity or radiation was involved.
The facility has a number of nuclear reactors and the research involves both nuclear weapons and nuclear power.
The fire occurred on a day Japan's new prime minister offered to consider selling nuclear power technology to India. The offer comes despite differences over signing a test ban treaty.
Tokyo has refused to allow Japanese nuclear companies to do business with India until New Delhi agrees to stop conducting nuclear tests.