Three employees of the Chhattisgarh State Electricity Board were killed on Tuesday and five Special Task Force personnel seriously injured in a landmine blast in Naryanpur district of Bastar region.

"The Maoists blew up a cement-laden truck near Kapsi, about 250 km from the state capital, by triggering a landmine, killing three CSEB employees, including the truck's driver," a police source in Narayanpur told PTI.

The injured STF personnel were admitted to Narayanpur district hospital, police said.

The incident occurred when the CSEB employees were going to Jharaghati with cement to repair three high-tension electricity towers that were blown up by Naxalites on June 1.

The damage to the towers has resulted in 27 lakh people of five districts in the Bastar region going without electricity for the past five days.

Police had earlier said the Maoists had planted landmines to target people being sent to repair the damaged towers.