Five security personnel were killed and seven injured on Monday after armed Maoists blew up a military vehicle in Chhattisgarh’s Dantewada district, in the fourth rebel attack in three days in the strife-torn Bastar zone.br br Armed guerrillas triggered a powerful improvised explosive device (IED) carrying over 50 kg of explosives that tossed an anti-landmine vehicle carrying 11 jawans of the Chhattisgarh Armed Force in the air, police said.