Suspected Maoists shot dead three people and injured two others at a village in Bihar's Gaya district on Monday.
The killings occurred between midnight and 1am at Amkola village, about 60km from the district headquarters.
The deceased were identified as Sanjay Yadav, an influential local whom the Maoists suspected of being a police informer, and two men said to be Sanjay's bodyguards, Bhuvaneshwar Yadav and Surendra Yadav.
"The attack came while the victims were attending a cultural programme they had been invited to by the village mukhia," said Nishant Tiwari, senior superintendent of police, Gaya.
"We have started combing operations to nab the Maoists involved in the killings."
He said the Maoist rebels landed at the venue of the cultural programme, separated Sanjay and his two alleged bodyguards from the crowd, and shot them. All three died on the spot.
Two others injured were rushed to Anugrah Narain Magadh Medical College and Hospital at Gaya.
The ultras also looted a rifle, a pistol, 100 live cartridges and Rs 5 lakh from the victims, before torching Sanjay's car.
Locals said the Maoists believed that information provided by Sanjay had to police raids on the ultras' hideouts.
Sanjay headed a group called Sashastra People's Morcha, which provided protection to villagers from Maoists.
Locals said Sanjay's brother-in-law Nitish used to be a Maoist sympathiser but was later declared a deserter by the rebels after he allegedly escaped with the 'levy' (protection money) collected by them from local traders.
This was the second Maoist attack in Gaya district in less than two months.
On September 16, two jawans of Bihar's Special Auxiliary Police (SAP) were killed when armed Maoists attacked a patrol party at Amarut village.