Suspected Maoist rebels blew up an ambulance with a land mine in eastern India, killing at least three people inside, a news report said Sunday.

The insurgents detonated the roadside mine in Kandhamal district of Orissa state on Saturday night, the Press Trust of India quoted police officer Manmohan Praharaj as saying. The victims were a patient, a female paramedic and the driver.

Rebel attacks in the area often hit government vehicles, but it wasn't known if the ambulance was targeted. No one has claimed responsibility for the attack in the Brahmanigaon region, nearly 720 miles (1,100 kilometers) southeast of New Delhi.

Police officers in the remote area could not be reached for comments on Sunday.

Inspired by Chinese revolutionary leader Mao Zedong, the rebels have been fighting in several Indian states for more than four decades demanding land and jobs for farmers and the poor. About 2,000 people — including police, militants and civilians — have been killed in the past few years.

The rebels are known as Naxals, after Naxalbari, the village in West Bengal state where the movement was founded in 1967.

The insurgents, who have tapped into the rural poor's growing anger at being left out of the country's economic gains, are now present in 20 of the country's 28 states and have an estimated 10,000 to 20,000 fighters.

Prime Minister Manmohan Singh has called them India's biggest internal security threat.