Unlike past attacks in the state, a lethal mix of RDX and ammonium nitrate — not less than 20-25 kgs — was packed in the cars used in last week’s blasts, creating a “heat wave” around a 200-metre radius that had a “burning and charring effect”. Officials suspect that while the bombs were made locally, both the RDX as well as the technology was “imported” from abroad.

According to experts, this kind of bomb which sends a several thousand degree centigrade heat wave is used in terror strikes in West Asia and Pakistan.

Meanwhile, the STF picked up two suspects, Muzamil Haq and Anarul Haq, from Tinthengia in North Lakhimpur district in connection with the Panbazar blast. Police said the duo had stolen the car which was used in the Panbazar attack.

“The bombs were made inside Assam. According to our estimate, not less than 20 to 25 kgs of RDX and ammonium nitrate were packed in each of the cars. It is impossible that they imported the bomb from outside the state,” said Padmapani, joint director of the forensic laboratory.

“The heat wave generated burns, and badly charred the victims,” added Padmamani. The victims were charred to their bones within a short time. The heat also charred cars and bikes.

Forensic experts also recovered a Progammable Time Delay device from the Ganeshguri blast site. “The PTD device is very sophisticated, since it can be timed for 24 hours. For example, an explosive-laden car with PTD can be parked in the morning, and the blast can be timed for next morning,” said a forensic expert, part of the probe.

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