The crude improvised explosive device (IED) used in the Sep 17 Agra blast that injured four people was "unique" in its design, investigators said on Thursday, adding that local welders had been contacted and a lead from Haldwani was also being followed.
"The significant part is the uniqueness of the design, especially the welding component - the manner it has all been done up. The device has an electronic and welding component," Deputy Inspector General Aseem Arun told IANS.
"While the electronics and explosives used are the usual ones, it is the welding that is the cause of uniqueness and worry...not seen this kind of design," he added.
"We have a lead from Haldwani which is being followed up," Arun said.
"It appeared to be some kind of crude bomb made by local firecracker experts, who used an intricate welding process," a police source added.
The low-intensity explosion took place Sep 17 around 5.30 pm at the reception area of Jai Hospital, situated on a service lane of National Highway-2, barely 2.5 km from the Taj Mahal, a declared terror target frequented by thousands of tourists -- domestic and foreign.
Local welders have been contacted and more than a thousand mobile numbers around the vicinity of the explosion are being screened, sources added.
The injured were given Rs 1 lakh each by state chief minister Mayawati and Rs 50,000 each from the Prime Minister's Relief Fund.
Director General of Police Brij Lal Verma announced a reward of Rs 1 lakh to anyone providing clues.
Local police ruled out any terrorist link.
The National Security Guard, National Investigation Agency, Anti-Terrorism Squad, Special Task Force, Intelligence Bureau and forensic lab are still in the process of reaching any definite conclusion.
Officials pointed out that the central teams will submit their reports to the union home ministry.
The earlier reports of rivalry among nursing homes resulting in the explosion, have now been ruled out.
Police teams were sent to Bareilly, Kanpur and Delhi, officials said.