According to a senior official of Joint Investigation Team, Bapi Mahato tipped them off about Amiya Mahato, who arranged for the equipment.

Officials said Amiya, who has been arrested, is an active member of PCAPA and had concealed the equipment at his home in a village in Manikpara. “Bapi gave his address and we recovered a good number of tools used by railway gangmen,” said the official.

The CBI took Bapi to his home in Rasua village, from where some equipment were recovered as well.

This was the first important seizure by the CBI, crucial to prove the involvement of the men in custody. Amiya will be produced in the Jhargram court on Thursday.

The agency has picked up another suspect — Mantu Mahato — a close associate of Bapi who had kept him company on the day of the attack. Mantu was caught from Kharagpur but he is yet to be formally arrested.

The West Midnapore police, meanwhile, arrested four persons from Duli village on Wednesday. The spot is close to Ranja forest where the security forces had killed at least eight Maoists.

The men allegedly provided medical treatment and shelter to the Maoists injured in the encounter.

Manoj Verma, Superintendent of Police, West Midnapore, said the four — Ganesh Mahato, Dinabandhu Murmu, Rohini Mahato and Khagen Mahato — were active members of the PCAPA. They were produced in a Midnapore court.

“We have recovered medicines and injections worth Rs 1.5 lakh from their houses in Majurkota village,” Verma said.

“They used to run the health center in a clandestine manner,” he added.

In a separate operation in Belpahari, Mangal Garai, a member of the Belpahari squad was arrested late on Tuesday night.

“We have also picked up an arms supplier to the Maoists,” Verma said.

The SP added: “We have seized a huge cache of arms and ammunition from him.”

He is a resident of Bihar’s Munger and was produced in court.