A team of National Investigation Agency and experts of National Security Guards have joined the investigation with Maharashtra Police to probe all angles to determine whether any terror outfit was behind the blasts in the city last night.
Investigative agencies were searching for clues as the CCTV cameras installed at Dena Bank, McDonald's and Bal Gandharva traffic square, near where the explosions occurred, have not yielded any evidence so far and some of them were non-functional, sources said.
They said the Maharashtra ATS, city Crime Branch and the NIA are looking for clues from the two bicycles as two of the four coordinated blasts last night occurred in their front carriers.
Explosives were strapped on these bicycles which appear newly purchased and investigators are trying to locate the shop from where these were bought in order to nail the perpetrators.
As reports said a black sticky substance with ammonium nitrate was used in the explosions, forensic experts are also trying to ascertain the concentration of explosives in the devices to zero in on the likely group behind the blasts.
According to sources, different terror groups use varied concentration of explosives in their "signature bombs".
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Reports have said battery operated detonators with digital timers could have been used to trigger the blasts.
Home Minister Sushilkumar Shinde said in New Delhi that the Centre has taken the near simultaneous explosions "very seriously" and investigators were looking for clues.
"We have taken it very seriously," he told reporters here after a high-level meeting which reviewed the security situation in the country in the wake of last evening's blasts in Pune. MORE