The blast was followed by a heavy exchange of fire between the security forces and the Maoists, said Vivekanand Sinha, Inspector General (IG) of Police, Bastar.

The exchange of fire was going on till the time of reporting.

The CRPF personnel were on a routine patrolling in Palodi of Kishtaram area in Sukma district when Naxalites set off an improvised explosive device (IED), blowing the vehicle at around 11 a.m, Sinha said.

There were 11 troopers in the anti-landmine vehicle, according to the officer.

The injured jawans were being airlifted to Raipur, Sinha said.

A large force has been sent to the spot, said D.M. Awasthi, Special DG (Naxal).