Calcutta, Nov. 12: Minutes after Shakil Ahmed died in the Burdwan blast, two of his phones sprung to life 140km away in Birbhum.

The two SIM cards issued in the name of Shakil were inserted into cellphones by Sajid, the Jamaat-ul-Mujahideen point man in Bengal, to make a series of calls within 30 minutes of the blast to alert operatives across Murshidabad, the National Investigation Agency has learnt.

Sources in the central investigating agency said Sajid was informed about the 'accidental' explosion by Zia-ul-Haque, a schoolteacher in Burdwan.

Both Sajid and Haque are now in NIA custody.

Within minutes of being told that Shakil had died in the Khagragarh flat, Sajid instructed Haque to inform members of the JMB in Burdwan while he took the responsibility of alerting the operatives in Murshidabad.

'Had it not been for Sajid's prompt decision to alert the other operatives, many more members of the terror module would have been arrested by now. He was cunning enough to use SIM cards that were registered in the name of a man who was dead by then,' an NIA officer said.

According to sources, Haque has told the investigators that he learnt about the blast from Rezaul Karim, an absconding suspect from whose Badshahi Road house 39 IEDs were recovered.

Haque then informed Sajid in Birbhum.

The NIA has learnt about several top JMB operatives who received the timely alert from Sajid.

Among them were Laden, who was based in Mukimnagar in Lalgola; Nasimullah, an expert in making explosives; Sadik, a Bangladeshi national who imparted training at a madarsa in Mukimnagar, and a worker at Burqa Ghar, a shop owned by Shakil in Beldanga.

Haque, on the other hand, informed Kodor Sheikh and Sheikh Yusuf in Birbhum and Burdwan, respectively.

'Sajid knew it was a matter of hours before the police would start hunting for him. He called only those he thought would be prize catches,' an investigator said.

What has surprised the investigators is Sajid's decision to instruct Haque to stay put in Burdwan while the others fled.

'Sajid had asked Haque to stay in Burdwan and keep an eye on the police. Haque had the perfect cover of being a schoolteacher. He kept Sajid posted for the next few days after the blast,' an NIA officer said.

Haque had apparently told Rezaul Karim over the phone to take shelter in the schoolteacher's Malda home.

After Haque's arrest in Burdwan last week, the NIA recovered Rezaul Karim's laptop from the Malda home where he had taken shelter for a few days.