India, Nov. 11 -- Investigation into the Red Fort car explosion of Monday evening, that killed 13 people, was handed over to the anti-terror agency NIA (National Investigation Agency) even though the cause of the incident remains unknown and the probe covering all possible angles.

While Prime Minister Narendra Modi and home minister Amit Shah on Tuesday vowed to bring the culprits of the explosion to justice, a terror angle - which opened up after the car, believed to be an i20, was traced to a doctor named Umar Un Nabi who investigators say is linked to a recent explosives haul in Haryana's Faridabad.

As investigators remained tight-lipped over the incident, source-based information across reports floated multiple details on the car in...