New Delhi, Nov 11 (PTI) Findings of the initial probe into the blast near the Red Fort suggest it may have been "accidentally triggered" while a hastily assembled explosive device was being transported, following the busting of an inter-state terror module, officials said on Tuesday.

Investigators have zeroed in on a Pulwama-based doctor, Umar Nabi, who was driving the car used in the explosion that claimed 12 lives, and had alleged links to the terror module busted with the recovery of explosives mainly from neighbouring Faridabad in Haryana.

On Tuesday, the Jammu and Kashmir Police took a DNA sample from Nabi's mother to establish the relation.

"The suspect was likely spooked after the raid in Faridabad which forced him to relocate hastily, increasing the chance of a mishap. The incident appears to have shifted from a suspected suicide attack to an unintended explosion during transport," a senior police officer said.

However, police are probing all angles, including suicide bomber attack, sources said.

The officer said that intelligence teams' first assessment suggests the improvised explosive device (IED) was assembled incorrectly, which limited its destructive effect.

"The bomb was premature and not fully developed, thus limiting the impact. The explosion did not create a crater and no shrapnel or projectiles were found," he added.

The Red Fort blast on a busy Monday evening came hours after eight people, including three doctors, were arrested and 2,900 kg of explosives seized with the uncovering of a "white collar" terror module involving the Jaish-e-Mohammed and Ansar Ghazwat-ul-Hind and spanning Kashmir, Haryana and Uttar Pradesh.

Meanwhile, the Delhi Forensic Science Laboratory has collected 40 samples from the blast site, which include mangled remains of the vehicle and human body parts, and these will be analysed for chemical traces. The laboratory has constituted a special team for analysis of samples, sources said.

The Delhi Police's FIR called the explosion "a bomb blast" as it invoked sections pertaining to conspiracy and punishment for a terror attack under the Unlawful Activities (Prevention) Act, officials said.

Initially, it was claimed that three people were in the car during the blast. However, it is now clear that only Nabi, who was on the run after the busting of the terror module, was driving the i20 car when the blast took place.

According to the police's investigation, it has also emerged that Nabi waited in the Sunehri Masjid parking lot for nearly three hours while searching on the internet about updates regarding his associates' arrest in Faridabad. The investigators have managed to establish an 11-hour trail of Nabi's vehicle.

He proceeded on Chhata Rail Chowk road near the Red Fort, then took a U-turn. The blast took place a few metres before the Red Fort police post, according to officials privy to the probe.

The car passed through multiple owners before being repurchased by Nabi on October 29. Its pollution under control (PUC) certificate was updated on the same day.

The multiple ownership of the car creates suspicion that this was part of the well-planned conspiracy.

The blast probe has been handed over to the National Investigation Agency (NIA), a decision taken after a review meeting chaired by Union Home Minister Amit Shah.

Among those arrested on Monday were Dr Muzammil Ganaie and Dr Shaheen Sayeed, both connected to the Al-Falah University in Faridabad, from where 360 kg of ammonium nitrate was recovered.

According to investigators, Shaheen was leading the Jaish-e-Mohammed's women recruitment wing in India. She headed the Jamaat-ul-Mominat, the group's female wing.

Nabi, whose name has emerged as the main Delhi blast suspect, hailed from Lethpora in south Kashmir's Pulwama district and was allegedly carrying explosives, possibly ammonium nitrate, in the car, they said.

A Delhi Police team visited the Al-Falah University in Faridabad and detained five to six people for questioning.

Police sources said the teams are checking CCTV cameras of the university to know more about the activities of the accused in the days leading up to the busting of the module.

Even as the police probe widened in the matter, an unsettling silence prevailed in the area near the Red Fort as police and FSL teams still remained at work in collecting evidence and remains of bodies from the blast site and its vicinity.

According to the FIR, the impact of the blast was such that the car was propelled several feet above the ground and the wall and the roof of the police chowki was damaged. Some body parts were even found in the car.

While no terror organisation has claimed responsibility behind the attack, investigators suspect the involvement of Jaish-e-Mohammed behind it even though they are also probing the involvement of other terror outfits.

Preliminary findings suggest ammonium nitrate, fuel oil and detonators may have been used in the blast that ripped through the slow moving car near a traffic signal.

As investigations into the blast and the terror module continue, officials said a man named Tariq from south Kashmir's Pulwama district had given the i20 car to Nabi, and is now under arrest.

Teams from Delhi Police, NIA and intelligence agencies have fanned out across Delhi and Kashmir. Four people have been detained in the raids in Kashmir. Of the four, two have been shifted for joint interrogation for their role in the Delhi blast as well as the inter-state terror module.

Several raids were also conducted at multiple locations in Delhi. The national capital has been placed on high alert with strict vigil being maintained at the airport, railway stations and bus terminals.

Hours before the blast, a social media post, titled 'Is something going on in Delhi?', was shared on Reddit. The user claimed that he noticed an unusually large presence of police and army personnel while crossing the area earlier that day.

Following the blast, security across the national capital has been intensified.

All vehicles entering Delhi, whether private or commercial, were being thoroughly checked and verified as part of heightened security measures, officials said.

An overnight search operation was conducted at hotels and guest houses in Daryaganj and Paharganj areas to trace possible suspects.

The Red Fort metro station has been closed for commuters and traffic restrictions imposed in the area.

Of 12 people who died in the blast, seven have been identified till now. One mutilated body was recovered from the mangled remains of the car, officials said. PTI BM SSJ SGV NSM SHB SLB VIT BUN KVK KVK