According to the official sources, the blast was triggered near the famed Ganesh Mandir when the area was busy with vehicles and commuters on the inter-state Guwahati-Shillong Road.
A woman and her child travelling in a car with her husband were seriously injured when debris from the blast hit them.
Another minor child and eight others were also wounded by stones thrown up in the blast.
The injured were admitted to GNRC hospital and two other seriously injured were sent to Gauhati Medical College Hospital.
Assam Police sources said that they were not informed about the preplanned blast in the quarry for traffic to be stopped and people moved away to safer places during the explosion.