At least 10 personnel of the Central Reserve Police Force (CRPF) were killed and seven soldiers were injured in an attack by Maoist rebels in a forest in Aurangabad district of Bihar, police said on Tuesday.
Police said three Maoists were also killed in the encounter that took place in Dumari Nala forest area on the border of Gaya and Aurangabad districts, 172km south of Patna.
Paramilitary forces have launched a combing operation in the area when a team of CRPF personnel got trapped after the rebels triggered around 21 improvised explosive devices (IEDs) and came under heavy firing on Monday night, police said.
Director-general of state police P K Thakur said eight soldiers were killed immediately and two of the five wounded died later in a hospital.
The bodies of three dead insurgents were recovered later, he said.
The CRPF personnel were conducting anti-rebel operations in the area where the Maoists have been fighting for more than three decades in central and eastern India, staging hit-and-run attacks against authorities as they demand a greater share of wealth from the area's natural resources and more jobs for farmers and the poor.
This is one of the biggest casualties of the elite Cobra unit which has been raised by the CRPF for undertaking special jungle warfare operations.
The CRPF's director general will visit Gaya on Tuesday to assess the situation.