NEW DELHI, India (CNN) -- Suspected Maoists blew up a bridge in eastern India Tuesday, killing seven police officers, authorities said.
Two police were injured in the blast in the Bastar district of India's Chhattisgarh state, police superintendent Pravir Das told CNN.
"Definitely it was a Maoist work," he said.
The officers were accompanying election officials to their office at Konda Gaon in the district. None of the officials were hurt.
The Maoists rebels, known as the Naxalites, have been battling the government in several states in an insurgency that has resulted in thousands of casualties since the late 1960s. They claim to be fighting for the poor and dispossessed.
Indian Prime Minister Manmohan Singh has called the rebels India's biggest security threat.
Last year, more than 800 people were killed in Naxal-related violence across the country, according to local media reports.