Around 1,100 people, including 426 security personnel, have been killed in Jharkhand since it was carved out of Bihar in November 2000, police data show.
The dead include a Lok Sabha member, two state legislators and an Indian Police Service (IPS) officer.
Superintendent of Police Amajeet Balihar was killed Tuesday in a Maoist ambush along with five other policemen.
The Maoists attacked a police convoy in the Kathikund forest in Pakur in Dumka district, 350 km from the state capital.
The Maoists first set off a land mine and later fired indiscriminately on the convoy. Balihar died on the spot.
In January 2005, Communist Party of India-Marxist Leninist legislator Mahendra Singh was shot dead in Giridih district.
More From This Section
In March 2007, Jharkhand Mukti Morcha Lok Sabha member Sunil Mahto was assassinated.
In 2008, former minister and Janata Dal-United legislator Ramesh Singh Munda was killed.
The number of civilians killed has shown a rising trend over the last five years.
It was 57 in 2008, 138 in 2009, 70 in 2010, 130 in 2011 and 169 in 2012.
"Civilians are worst affected in rural parts. Villagers are targeted if one Maoist group perceives that they support a rival group. There are more than six Maoist groups in the state and civilians are being killed in internecine war," a police official told IANS.
When Jharkhand was carved out of Bihar, only eight districts were disturbed by Maoist activity. There are now Maoist guerrillas operating in 18 of state's 24 districts.