Home Minister P Chidambaram on Tuesday said something must have gone "drastically" wrong in Chhattisgarh where a CRPF patrol during Operation Green Hunt came under Naxal attack.

"The casualty is very high and I am deeply shocked at the loss of lives...This shows the savage nature of CPI(Maoist) and their brutality and the savagery they are capable of."

"Senior officials will be reaching their shortly," he said.

Chidambaram also met the Prime Minister after the attack.

"Government of Chhattisgarh and CRPF together had planned this operation. They had mobilised both the state forces and the CRPF but something has gone drastically wrong. They seem to have walked into a trap set by Naxalites," he said.

Chidambaram said he was very "sorry" for those who lost their lives in the attack.

In one of the biggest setbacks to 'Operation Green Hunt', at least 40 CRPF personnel, including a Deputy Commandant, were killed when Naxals ambushed them in the Mukrana forests of the Dantewada district in Chhattisgarh today morning.