New Delhi: Forty-eight hours after the explosion near a CRPF school in the national capital, the Delhi Police has not been able to identify the suspect. The police investigations, sources say, has severely been affected by the poor quality of CCTV cameras installed in the area. "Despite a high alert in the area and extensive investigation efforts, no arrests have been made so far. CCTV footage from nearby camera shows blurry image of several individuals, who are potential suspects in the case," the source said.According to the source, over 100 CCTV footages around the crime scene and on the routes leading to and from the location have been reviewed so far. At least two dozen people have been questioned but the police have not got any lead so far."No concrete suspects have been identified in the CCTV footage during the investigation. Only blurry images of two individuals have been seen, but their faces are not clearly visible," the source said.Possible Khalistani Link Being ProbedThe Delhi Police Monday wrote to the social messaging app Telegram for information about a 'channel' which claimed that the blast. Hours after the blast on Sunday, a purported Telegram post by a channel named 'Justice League India' was circulated on social media with a video of the blast with a "Khalistan Zindabad" watermark at the bottom.A Delhi Police source said, "The police have written to Telegram to know the details of the creator of Justice League India."Man In White T-shirt Seen Loitering At Blast SiteThe police investigations have narrowed down a person in a white T-shirt who seen loitering at the site of the blast on Saturday night. Officials, however, are not sure if he planted the explosive. "But we cannot confirm at this point if he planted the bomb," a police official added.The place witnesses a heavy rush of people at night as there are several eateries located on the opposite side of the blast site, an officer said.The strong blast ripped through a wall of the school in Rohini's Prashant Vihar area on Sunday morning. No one was hurt in the blast but a signboard, hoardings of nearby shops and window panes of vehicles parked near the spot were damaged.Police are also trying to ascertain the composition of the bomb, which was suspected to be placed one foot deep near the school wall.It is suspected that the bomb was made with a mixture of three chemicals -- hydrogen peroxide, borate and nitrate -- weighing more than two kgs and it was wrapped in a brown coloured packet, a police officer told PTI.Police sources suggested that the explosion may have been caused by a "chemical bomb," created by combining various chemicals.In the FIR, police mentioned a "white powder found scattered" at the site and said the explosion was caused by an "unknown explosive substance".An FIR under Sections 326(g) (mischief with severe consequences to public safety) of Bharatiya Nyaya Sanhita, Prevention of Damage to Public Property Act and Explosives Act was registered at Prashant Vihar police station.The FIR stated that there had been a "loud noise accompanied by white fumes of smoke" near the outer boundary wall of the CRPF Public School on Lancer Road.