At least 31 suspected Maoist rebels were killed in a battle with Indian troops in central India, police said Saturday.

The fighting erupted on Friday when counterinsurgency troops, acting on intelligence, cornered nearly 50 suspected rebels in the Abhujmaad forest area along the border of Narayanpur and Dantewada districts in Chhattisgarh state, said state police Inspector General Pattilingam Sundarraj.

Sundarraj said the operation was launched on Thursday, and the battle began the next day, lasting about nine hours. He said search operations were continuing in the area and that the troops had recovered some arms and ammunition, including automatic rifles. There were no reports of casualties among the troops.

There was no immediate statement from the rebels.

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 local villagers, 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 local villagers and have promised to fight for a better future especially in Chhattisgarh, one of India’s poorest states despite its vast mineral riches.

Authorities say at least 171 militants have been killed so far this year in Chhattisgarh.

Friday’s fighting was the deadliest clash this year.

In April, government forces killed at least 29 suspected Maoist rebels in in Chhattisgarh, three days ahead of the start of India’s national election.

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.