The militants lobbed the bomb at the house of Superintendent Engineer of Irrigation and Flood control department S Dhanabir at Tangmeiband near here, the sources said.
The bomb exploded injuring a boy identified as Dawa (11) who is helper in the family, sources said, adding the condition of the boy was stated to be out of danger.
No individual or group as claim responsibility so far.
Sources said police would investigate whether the bomb explosion was connected with monetary demand from the official.
Dhanabir, however, said no militants outfit has served him any monetary demand.