The bomb that exploded in Pune last week was made by mixing ammonium nitrate with potassium chlorate and small ball bearings were used as shrapnels to inflict injuries, but there was no gelatin or RDX in it, Maharashtra ATS said on Thursday.
"The forensic reports we have received suggest that the Improvised Explosive Device (IED) which exploded (in Pune) was a mixture of ammonium nitrate and potassium chlorate.
Small ball bearings, like the ones used in cycles, were used as shrapnels. But there was no gelatin, RDX or Trinitrotoluene (TNT) in the bomb," Anti-Terrorism Squad (ATS) chief Himanshu Roy said in Mumbai.
An analogue clock was used as a trigger for the low intensity bomb, he said.
The IED would have caused much more damage had the perpetrators not miscalculated their move, he observed.
"My sense is that there could have been much more damage due to the blast. But much of the impact went to the ground. Someone must have miscalculated the way in which the bomb goes," he said.
Although the blast was described as "prima facie" a terror attack, the investigators are yet to identify the perpetrators. "We cannot point out on a specific organisation behind the blast as of now, but the investigation has gone in a certain direction," Roy said.
The blast, caused by an IED planted in a motorcycle at Faraskhana police station's parking lot on July 10, had left five persons injured, including a police constable.
The motorcycle belonged to policeman Dadasaheb Rajge and was stolen on June 25 from district court in Satara. Rajge had filed a theft case on June 27.
Faraskhana police station is located close to Dagdusheth Halwai Ganesh temple, which has been on the terrorists' radar for quite some time.
In 2010, a suspected Indian Mujahideen (IM) operative Qateel Siddiqui had made a failed attempt to plant a bomb there. He was found strangulated to death in Yerawada Central Jail in June 2012.
A case has been registered under sections 307 (attempt to murder), 324 (voluntarily causing hurt by dangerous weapons or means), 120 (B) (criminal conspiracy), besides various sections of the Explosives Act and Unlawful Activities Prevention Act in Pune.