Congress leader in-charge of Bihar affairs Gulchain Singh Charak said nothing short of a CBI probe would be acceptable to the party and asked Chief Minister Nitish Kumar to hand over the firing case to CBI for an impartial and speedy probe.
Describing the firing as "unprovoked and shameful," Charak said the chief minister must apologise for the incident.
"Complete jungle raj prevails in Bihar as the situation is registering marked deterioration every day under a government which claims to have established rule of law," he said.
Four people were killed and scores others injured in firing and clash between policemen and locals opposing construction of a starch factory and approach road at Bhajan village under Forbesganj Industrial Area in Araria district on June 3.
He requested the chief minister to personally visit the area and try to find out a solution to the issue raised by the locals.
Demanding that Deputy Chief Minister S K Modi's role in the incident also be probed, Charak said Modi was alleged to have visited the area three days before the firing taking place and had reportedly ordered the authorities to ensure construction of the factory using force.
"Since Modi is also alleged to be involved in the incident, it will require a probe by an independent investigating agency like CBI instead of a judicial probe," he said.
Earlier, he participated in a sit-in demonstration organised by the state Congress at the Kargil Chowk here to press for the CBI probe.