The Assam government has declared state mourning in memory of those killed in Sunday's blast in Dhemaji town.
Seventeen schoolchildren, including nine girls, were killed and 40 injured in the blast, which took place at an Independence Day function.
The national flag will fly at half-mast on Monday and government employees throughout the state will wear black badges to denounce the act, an official spokesman said.
Condolence meetings are being held in all district and subdivisional headquarters to protest against the incident.
Meanwhile, in Dhemaji and Lakhimpur districts, normal life was paralysed due to 12-hour bandh called by the All Assam Students' Union.
The bandh was spontaneous with all schools, colleges and educational institutions, shops and other business establishments closing down.
There was little traffic on the road and attendance in government offices and banks was thin.