Eastern India, a largely rural area with a lot of poor people, and a fair amount of social injustice (feudalism and corrupt officials thrive out there), has proved fertile ground for a home grown communist (Maoist) insurrection. As the rebels become bolder, and make more spectacular attacks, the government has responded with police reinforcements. On paper, the most hard hit state, Chhattisgarh, has 206 police per 100,000 people (compared to an average of 125 for all of India). But in reality, most of those police units are undermanned, and still waiting for replacements. The actual number of police per 100,000 population is only 86. That's a big reason why Chhattisgarh is still a dangerous place for cops, as well as anyone with too much money (according to the local communist activists) or political views the Maoists disagree with. The police are having a hard time even recruiting locals to serve in the police, much less people from outside the area.
What's amazing is that communist rebels and terrorists are still active, 18 years after the collapse of the Soviet Union, the end of the Cold War, and seeming defeat of the communist movement. But there is still an energetic communist terrorist operation going on in Indian state of Chhattisgarh. These terrorists belong to the Maoist movement, an organization trying to establish communist dictatorships similar to radical communist movement of the 1960s, when Chinese ruler Mao Zse Dong sought to "purify" the country of anti-social (non-communist) elements. The Cambodian Khmer Rouge were the first copy-cat Maoists, and they killed over a million of their countrymen in the 1970s.
Leftist parties are strong in India, particularly at the state level. There are two Communist Parties, and two other leftist parties that comprise the "Left Front". They control about six percent of the seats in parliament, and even more at the state level. These leftists have long prevented the government from going after the Maoist rebels in a big way. That has changed in the past few years, as the Maoists became more violent. Last year, in Chhattisgarh state alone, Maoists killed 241 people, while losing nearly 700 of their own members (82 killed, the rest arrested.)