NEW DELHI (AP) — Maoist rebels on Saturday shot and killed at least 11 Indian paramilitary soldiers in an ambush in central India, police said.

The attack also left three soldiers wounded in the rebel-infested Sukma forest area in Chattisgarh state, top police officer R.K. Vij said. It wasn’t clear if any rebels were killed or injured when the Central Reserve Police Force soldiers returned fire, he said.

The Press Trust of India news agency said the rebel attack targeted more than 100 soldiers who had gone to the area to clear a road blocked by the insurgents.

The insurgents, who say they are inspired by Chinese revolutionary leader Mao Zedong, have been fighting for more than three decades in central and eastern India, staging hit-and-run attacks to press their demand for a greater share of wealth and more jobs for farmers and the poor.

The government says the rebels are India’s biggest internal security threat. According to the Home Ministry, they operate in 20 of India’s 29 states and have thousands of fighters.