The incident occurred at 9:40 AM when the policemen were moving for an operational task in the forest between Pavimuranda and Murmuri villages in Chamorshi taluka of the district.
Officials said the slain security personnel belong to the specialised C-60 anti-Naxal operations force of Maharashtra and the blast took place when their vehicle was moving along the Murmuri-Chamuri axis of the district.
"We have lost seven of our men in the attack carried out by Naxalites.The incident occured in Gadchiroli," a senior police officer said.
After the landmine blast, there was an exchange of fire between the police and Maoists.
Firing is still going on in the forest area, police said.