The death toll in Thursdays bomb blast at Jalpaiguri rose to six when one of the injured undergoing treatment at North Bengal Medical College Hospital succumbed to injuries on Saturday. Five persons were killed and 11 injured in the explosion at Barjrapra bridge Thursday. Though Kamptapur Liberation Organisation (KLO),fighting for a separate state of Kamtapur in north Bengal,was suspected to be behind the blast,the outfit has refused to take responsibility for it. Gautam Deb,minister for North Bengal development,said external forces were behind the blast. A National Investigation Agency team visited the place Saturday to collect samples.