A small explosion rocked the National Medical College and Hospital in Kolkata injuring two persons, police sources said.
Two sweepers of the hospital were injured when a plastic container containing some carbide material exploded with a bang when they tried to shake it, the sources said.
No patient was, however, injured, police said, adding, it was a small explosion.
The bomb squad personnel have arrived to investigate the matter.
The college principal Shiddhartha Chakraborty said normal hospital services were not affected.