An explosive weighing around 40-50 kg was used. (File)
The Chhattisgarh police on Friday said the powerful improvised explosive device (IED) that exploded killing 10 policemen and a civilian driver in Dantewada had been planted by Maoists at least two months ago.
The explosive, however, remained "undetected" during the demining exercise conducted a day before the attack on Wednesday, they said.
Ten personnel, belonging to the District Reserve Guard (DRG) of police, and a civilian driver were killed after Naxalites blew up a multi-utility vehicle (MUV), which was part of a convoy carrying security personnel in Aranpur police station area of Dantewada on Wednesday afternoon.
The incident occurred around 1 km from Aranapur police station on the road that goes to Dantewada district headquarters.
"The preliminary investigation suggests that the IED was planted at least two months ago or before it. The grass had grown on the layer of soil under which the wire, which was connected to the explosive, was concealed," Inspector General of Police (Bastar range) Sundarraj P told PTI.
An explosive weighing around 40-50 kg was used and it seems that it was placed 3 to 4 feet beneath the road by digging a tunnel from roadside, he said.
A demining exercise to detect explosives was conducted on the same road a day before the attack, but neither an IED, nor any suspicious object was traced, the IG said, adding that an investigation is underway to ascertain how the explosive remained undetected.
Nearly 200 security personnel from the CRPF and state police's DRG launched an operation from Dantewada district headquarters on Tuesday night after getting information about the presence of Maoists belonging to the Darbha division in the area, police had said.
When asked if there was any violation of the standard operating procedure (SOP), the IG said, the personnel followed the operational tactics.
"The operation was launched after getting information about presence of Maoists belonging to Darbha division formation. On Wednesday morning, an exchange of fire took place between security personnel and Maoists a few kilometres away from Aranpur following which two Maoists were apprehended. One of them was injured," he said.
Subsequently, a DRG team set out from Aranpur for Dantewada base in eight vehicles, while other teams of security personnel were carrying out searches at the encounter site, he said.
"The apprehended Maoists were being brought in the first vehicle (of the convoy). There was a long gap between each vehicle to avoid appearing like a convoy. The Maoists targeted the second vehicle, with 10 policemen onboard," the official said.
Around 200 metres before the attack site, some local tribal youths were stopping passersby to collect money for Beej Pandum, a local festival, which is a usual practice, he said.
While they don't ask for money from the police, security personnel sometimes voluntarily give a small sum to tribals for the festival. As of now, it is unclear whether the vehicle which was targeted had stopped there to give money to tribals, the official said.
The IG further said that he suspects that any militia member could have been present along with locals there to conduct a recce on police personnel and passed on information to Maoists who triggered the blast.
However, further investigation into the matter will throw more light into it, he added.
Beej Pandum is a festival celebrated by the tribals in Chhattisgarh ahead of the sowing season with the onset of monsoon.
When asked about the involvement of any senior Naxalite leader in the attack, the IG said the Darbha division committee of Naxalites has claimed responsibility for the attack in a statement and its commander Jagdish is instrumental in Maoist activities in the area.
Malangir area committee of Maoists, which operates under Darbha division, could be behind the attack, but the investigation is underway, he said.
A police official on condition of anonymity said security personnel perceived low threat on the route, as road construction on the axis has been complete up to Kamarguda, which is around 25 km away from Aranpur.
The initial work on a 5 km stretch between Kamarguda and Jagargunda (Sukma) has been completed and its black top work will be completed in the next few months, he said.
On the day of the attack, a village market was also held in Aranpur and the presence of militia members of Naxalites cannot be ruled out, he added.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)