Central investigators probing the 2 October blast in West Bengal's Burdwan district on Friday seized a large stockpile of crude hand grenades, socket bombs and explosives from a house where suspected militant Rejaul Karim used to stay.
National Security Guard (NSG) and National Investigation Agency (NIA) officials found at least 30 hand grenades in the toilet of a house near the site, which was searched and sealed by the state police eight days ago.
The explosives were found in a secret loft constructed after cutting the wall of a bathroom in Rezaul's place. Security officials defused the bombs at the banks of Damodar River in Burdwan area.
The house is located at Mathpara on Badsahi Road near Khagragarh where the accidental explosion on 2 October killed two suspected Jamaat-ul-Mujahideen militants and injured another. Several people, including the two women have been arrested in this connection.
The West Bengal police had arrested two women from the house where the blast took place. The two women, who are now in NIA custody, were radicalised in violent Jihadi ideology at the madarsa.
The house was vacant at the time of the raid and six men living there who claimed to be masons, had decamped. Among those absconding is Rezaul, suspected to be the king pin among the Jihadis.
A NIA team had, on Thursday, searched the areas surrounding a madarsa in Simulia near the explosion site.
NIA had on Wednesday conducted searches at various places, including the residence and shop of the arrested accused Hashem Moulla alias Badre Alam, in Burdwan.
Besides arresting six people in Bengal and six others from Assam in connection with the incident, NIA sleuths have also interrogated three people in Chennai.
The arrests and the seizure of arms could be cue to a joint plan by al Qaeda and ISIS to target Indian cities, Director General of NSG Jayant Choudhury said on Thursday.