“Two BSF constables and the driver of the vehicle were killed,” additional director general of police (Anti-Maoist Operations) RK Vij said.
Another BSF vehicle in the convoy had a miraculous escape.
“The polling parties in Sukma had earlier reached the district headquarters safely,” Vij said.
Earlier in the morning, a Central Reserve Police Force (CRPF) deputy commandant was injured in an encounter with Maoists in south Bastar.
Maoists also opened fire on the forces retuning to the base camp.
In another incident, a CRPF jawan was injured in Kanker district in a blast triggered by Maoists.
All the injured personnel were air-lifted to Raipur for medical attention.
The Bastar zone registered nearly 70% voter turnout on Monday, as people defied Maoists’ poll boycott call. The second and last phase of polling in the state will be held on November 19.