Maoists, who are observing a 24-hour shutdown, blasted a mobile phone tower in Bihar's Saran district early on Wednesday, police said.A group of armed Maoists used a dynamite to blast the mobile phone tower at a village under Maker police station in Saran, police said.Police have launched a combing operation in the area.The rebels are observing a 24-hour shutdown to protest alleged police atrocities against their supporters.