Investigators probing the two blasts in Hyderabads Dilsukhnagar area suspect that the bombs were made of ammonium nitrate and used a fuel-oil booster,a quartz timer and aluminium casings. The timers are thought to be similar to those used in the low-intensity bombs that went off in Pune last August,they said Friday.
The first clues came as the death toll in Thursdays twin blasts rose to 16. Ninety people were wounded in the attack.
Investigators from the Andhra Pradesh police,the NIA and the NSG who reconstructed the explosions after visiting the sites found that the bombs may have used a quartz timer and aluminium casings.
A senior Andhra Pradesh police officer apprised of the efforts to reconstruct the bombs by AP explosives experts said the investigators had suggested possible similarities with the Pune blast.
The National Security Guard has reported the finding of a quartz timer or an electronic clock of some sort. This is a bit like the Pune blast timers. But we are only saying at this stage that a timer device was used, an AP police expert said.
The two bombs were designed to direct the impact of the explosion towards cylinders and inflammable items kept in nearby eateries,in a bid to cause maximum damage. Preliminary findings also suggest that ammonium nitrate was used along with a fuel-oil booster in the bombs,which did not weigh more than 600 gm each.
It is believed the bombs,packed in aluminium containers,were positioned on bicycles to give them elevation and angled to target crowded eateries nearby. They are also believed to have contained batteries with 3-9 volts of power. Fortunately the cylinders were not hit,otherwise many more could have died, said an officer. Most victims suffered head injuries and blacked out.
A team of NSG bomb experts who visited the blast site,however,said the directional nature of the bombs as well as the fact that they presumably had neither ball bearings nor shrapnel made them distinct from the failed Pune blasts. The IEDs recovered in Pune were not directional and had ball bearings and shrapnel. This is a major difference. If the same terror module was involved in the blast,they have definitely changed their modus operandi, said one officer.
Union Home minister Sushil Kumar Shinde,who visited the spot Friday,said: Two cases have been registered in connection with the blasts. The NIA (National Investigation Agency) will investigate the case in conjunction with the Andhra Pradesh Police. The first explosion took place at 6.58 pm and the second at 7.01 pm,he said. Investigators have arrived at the exact timings of the blasts from CCTV footage from near a traffic signal near the Konark theatre where the
second blast occurred.
The CCTV footage does not cover the site where the bombs were placed but they pick up the sound of one explosion and the flash of the second. That is how we arrived at the time of the blasts as 6:58 pm and 7:01 pm. The first blast occurred near the Venkatadri theatre and the second near the Konark theatre some 100 metres away, a senior AP police officer said.
Eleven people were killed in the second blast. The death toll in the first blast was lower as a road separated people from the direct impact of the bomb placed behind a bus stop.
While no evidence of shrapnel being used in the bombs has been found,investigators are surprised by the presence of shrapnel wounds and nuts and bolts in the bodies of the dead and the injured.
A few of the injured had nuts and bolts in their bodies. We do not know if they were kept with the bombs or are a result of the explosion. We have to reconstruct the crime scene after collecting these nuts and bolts from the bodies of the victims, the Andhra Pradesh police expert said.
Heavy movement of people at the site of the explosions,however,compromised much of the evidence,while VIP visits during the day made matters worse.
Investigators have also hit a dead-end in terms of the bicycles on which the bombs were placed. They seem to be old cycles,possibly stolen. They have no markings to indicate the brand. These were possibly removed. This has not provided leads, an officer said.