Relief over the relatively peaceful April 10 polling in Bastar in Chhattisgarh evaporated on Saturday, as Maoists blew up a bus taken by polling official and an ambulance by Central Reserve Police Force personnel, killing 14 and injuring several, in the State.

In one of the deadliest acts of election-related violence, Maoists blew up the ambulance, 'Sanjivani 108,' near the Darbha Valley in Bastar, killing five CRPF personnel and two ambulance technicians. Five CRPF personnel were injured, the police said.

Earlier, seven polling officials were killed and three were seriously injured when Maoists blew up a bus carrying polling officials in the Ketunlar area, 22 km from the district headquarters of Bijapur.

"The polling officials were advised to walk and not to use any vehicle. But they were tired and boarded the bus, which was blown up in a landmine blast," said Arun Dev Goutam, Inspector-General of Police, Bastar range.

Chhattisgarh Chief Minister Raman Singh condemned the attack, and said the Maoists were enemies of democracy.