Naval divers were pressed into operation to look for the missing personnel of an elite anti-naxal Force, who were feared drowned in a reservoir at the Andhra Pradesh-Orissa border, where their launch sunk after being fired upon by Maoists.

The incident has turned out to be the biggest blow to the force in its two-decade-old history.

Naxals have never targeted the elite force in such a brazen manner. While five deaths have already been confirmed, the toll may go up significantly as hopes of finding the missing men are fading.

State Home Minister K Jana Reddy, who reached Visakhapatnam [Images] today morning, said that the exact number of missing security personnel was not clear. "We are not in a position to give a figure at this point," Jana Reddy said.

Director General of Police SSP Yaday told the media that the search and rescue operation was going on. "We think 30 to 35 men are missing," he said.

The attack on the Greyhound force comes barely two days after the Union Home Secretary showered praise on the force, hailing it for bringing the Maoist violence under control in Andhra Pradesh. The Central government has even urged other Naxal-affected states to create similar forces.

A massive operation has been mounted by the Navy and the state police to trace the missing policemen.

Six helicopters belonging to the Navy and the Oil and Natural Gas Commission are combing the Machkund reservoir. Inspector General of Greyhounds Rajiv Trivedi was supervising the operations.

A team of Indian Navy's divers was also helping in the search.

The doctors at the Seven Hills hospital in Visakhapatnam said that the condition of three injured policemen was critical, but the remaining eight were stable.

Confusion prevailed about the kind of weapon used by the Maoists to target the launch, in which the Greyhound and police personnel were returning after a joint operation in Orissa. The Maoists reportedly used a rocket launcher to target the launch and took at least three people, including the driver of the launch, as hostages.

Senior police officials in Hyderabad admitted that the Greyhound personnel had taken no precautionary measures. "All the commandos and other police personnel took the same boat, which was a blunder. They should have been on two separate boats to deal with any ambush," said an official involved in anti-Maoist operations.

The top brass are also worried about how the Maoists received information about the location of the launch.

The spot at which the Naxals launched their attack is located near Bodikottu, between two hillocks.

The officials admit that the Greyhound commando's lack of training in water warfare has also contributed to the tragedy. "The commandos are trained in jungle warfare only," said the source.

Chief Minister Y S Rajasekhara Reddy is expected to visit the spot today afternoon.

UPA chairperson Sonia Gandhi [Images] contacted the Chief Minister over phone today morning and expressed her concern over the incident. Sources said that she inquired about the search operation and asked the Chief Minister to take the necessary measures to rescue the missing men.