Patna, Oct 18 (IANS) As many as 57 people were booked in Bihar's Aurangabad district Friday, a day after seven people were killed in a massive landmine blast triggered by Maoists.

There was tension in the area and the first information report (FIR) was lodged against seven people who were named and 50 "unknown" people, police officials said.

Combing operations have been intensified against Maoists in Aurangabad, which is considered their stronghold, officials said.

"Search operations against Maoists were intensified Friday," Additional Director General of Police Ravinder Kumar said.

He said district police have lodged an FIR and top police officials have been camping in Aurangabad.

"There is tension in the village but it is under control," he said.

The blast took place near Pisai village Thursday evening within Obra police station jurisdiction in Aurangabad, about 120 km from here.

Sushil Pandey, husband of a district council member, was among those killed in the land mine blast, police said.

According to a district police official, Pandey, a former commander of Ranvir Sena, an outlawed private army of landed upper castes, was on the hit list of Maoists and they had threatened to kill him after he was released from jail recently.

The state government transferred Aurangabad Superintendent of Police Daljeet Singh, who has been replaced by Upendra Kumar Sharma. The government also announced an ex-gratia of Rs.5 lakh for the next of kin of each of the dead.

Opposition Bharatiya Janata Party (BJP) targeted Chief Minister Nitish Kumar for the incident and demanded strict action against Maoists. 

Senior BJP leader and former deputy chief minister Sushil Kumar Modi during his visit to the village, where he met families of the victims, blamed Nitish Kumar for the killing of seven people.

Another BJP leader admitted that those killed in the landmine blast were from upper castes, the support base of the party in Bihar.

"BJP has to raise the killings of upper castes by Maoists to send a strong political massage to protect them," the BJP leader said.

However, ruling Janata Dal (United) spokesperson Neeraj Kumar said there was no justification for the BJP's blame game politics.

"None other than chief minister directed that the combing operations be intensified in the district to flush out Maoists. There is no question that state government will allow some vested interest to create social tension in the state," Neeraj Kumar said.