A massive manhunt is on by the security forces in Assam to nab the culprits involved in the blasts in Guwahati and Dhubri. One CRPF personnel was killed and 12 persons were injured in hand grenade blast at Paltan Bazar area in Guwahati at 7.45 pm on Saturday. State Home Secretary said the blast was the handiwork of anti-talk faction of ULFA. Another 12 persons were injured in a grenade blast at Doomdoma in Tinsukia on Thursday.State Law and Order IGP said that police picked up four ULFA linked men in this connection.Indefinite curfew has been clamped in Dhubri Police station area after miscreants hurled patrol bomb at I G Road in Dhubri district. One person was killed and two others were seriously injured in the incident.Indefinite curfew has also been clamped at Bilasipara sub-division in Dhubri district along with Dhubri town area.Army, Rapid Action Force and para -military forces have intensified search operation to nab the culprits. Additional forces have been deployed at Dhubri town.AIR Correspondent reports, security forces have intensified search operation in both Guwahati and Dhubri to arrest the culprits. Police is examining all options including the involvement of anti-talk faction of ULFA in grenade blast incident at Paltan Bazar in Guwahati.On the other hand, a strict vigil is being maintained by army and Rapid Action Force to avert further disturbance at Dhubri town. Official sources said additional security forces will be deployed in Dhubri district.Condemning the blasts, various civil society organisations urged people to maintain peace and harmony.