At least 31 suspected Maoist rebels and two police officials were killed on Sunday in the deadliest combat so far this year in central India, police said.

Hundreds of police and paramilitary soldiers launched an operation in the forests of the Indravati area of Chhattisgarh state based on intelligence that large number of rebels had gathered there, said state police Inspector General Pattilingam Sundarraj.

Sundarraj said as the troops conducted a search operation fighting erupted in the forest, killing at least 31 insurgents and two police officials. Two other police were injured. He said search operations were continuing in the area and the troops had recovered some arms and ammunition, including automatic rifles.

There was no immediate statement from the rebels.

Sunday’s fighting is the biggest so far this year and the second major clash in less than a month in Chhattisgarh, according to police officer Jitendra Yadav.

At least 16 rebels were killed in the state’s Gariband district on Jan. 23. According to Indian officials, the government had issued a bounty for 12 of them totaling about $345,000. Eight rebels were killed in a gunbattle with troops in the Bijapur district on Jan. 31.

Indian soldiers have been battling the Maoist rebels across several central and northern states since 1967, when the militants, also known as Naxalites, began fighting to demand more jobs, land and wealth from natural resources for the country’s poor indigenous communities. The insurgents are inspired by Chinese revolutionary leader Mao Zedong.

Years of neglect have isolated many locals, who face a lack of jobs, schools and health care clinics, making them open to overtures by the rebels. The rebels speak the same tribal languages as many villagers and have promised to fight for a better future especially in Chhattisgarh, one of India’s poorest states despite its vast mineral riches.

The rebels have ambushed police, destroyed government offices and abducted officials. They’ve also blown up train tracks, attacked prisons to free their comrades and stolen weapons from police and paramilitary warehouses to arm themselves.