The RJD leaders through memorandum submitted to District Magistrates also demanded a compensation of Rs 10 lakh for the victims' families and government job to one family member each.
They demanded that a case under IPC 302 (murder) and 120-B (criminal conspiracy) be registered against the chief minister and Education Minister P K Shahi for alleged laxity.
The protest dharna at Chhapra was led by newly elected Lok Sabha member from Maharajganj seat Prabhunath Singh while in the state capital, party secretary general Ramkripal Yadav and others held a sit-in.
"To bring truth of the midday meal death to the public it is necessary that CBI probe the matter," Ramkripal Yadav said.
He alleged that instead of discharging its responsibility, the JD(U) government in the state was trying to cover up the incident and give a political colour to it.
Education minister P K Shahi had highlighted that supplier of items for the midday meal Arjun Rai, husband of the Principal Meena Devi, was an active worker of a party (RJD).