Bhubaneswar: A day after four persons were critically injured in a crude bomb explosion in Airfield area here, National Investigation Agency (NIA) on Wednesday launched a preliminary inquiry into the incident.The blast occurred while the bomb was being assembled on the rooftop of a house, leaving criminal Sehnawaz Malik, 26, and three others critically injured. The injured persons are admitted to the intensive care unit of a private hospital.An NIA team visited the site of the explosion and questioned the houseowner. Officers said that while no terror link or suspicious elements have emerged so far, the agency is not ruling out a conspiracy angle.“Since the explosion involved a history-sheeter, we want to verify the circumstances and assess whether the case falls under our jurisdiction. At present, this is only a preliminary inquiry. If suspicious angles emerge, we will formally take over the case from police,” an NIA source said.Commissionerate police are investigating the motive behind the manufacture of high-intensity bombs. “Once the prime suspect recovers, his interrogation will provide clarity. Statements of the other injured will also be recorded,” said DCP Jagmohan Meena.Police sources revealed Malik has seven prior cases against him. He was released on bail six months ago following a political clash in Nayapalli. Investigators are now probing whether Malik acted alone or had accomplices, and whether the bombs were intended for criminal activities or political violence.The incident has sparked concern among residents, who are demanding stricter action against habitual offenders. “We have intensified vigilance in sensitive pockets of the city to prevent recurrence,” a senior police officer said.The blast comes close on the heels of an explosion outside a school in Mancheswar on Nov 28 last year during President Droupadi Murmu’s visit to the city. While NIA’s inquiry then ruled out a terror angle, city police are yet to identify those responsible for hurling bombs in broad daylight.light.