The explosion took place in Jalpaiguri district, police said.
"Seven persons received injuries. The bus was bound for neighbouring Bhutan from Assam. The National Liberation Force of Bengalis has claimed responsibility for the blast," said Superintendent of Police (Jalpaiguri) Amit Javalgi.
The injured were admitted to hospital.
Javalgi did not immediately elaborate upon the National Liberation Force of Bengalis -- the organisation that had claimed responsibility for the explosion.
--IANS (Posted on 18-08-2013)