Muslims unload bodies of riot victims wrapped in bamboo mats (Pictures: Subhamoy Bhattacharjee)
Police in the north-eastern Indian state of Assam are using helicopters to spot rioting mobs as the death toll in days of violence has risen to 47.
More than 100 people have been injured in the riots that have now spread to new areas in the state, officials say.
More than 85,000 people have fled their homes and taken shelter in government camps set up mainly in schools.
The clashes broke out on Friday between Bodo tribespeople and Muslim settlers from Bangladesh in Udalguri district.
The groups have been fighting with bows and arrows, machetes and guns, and several villages have been set on fire.
Police have imposed a curfew and have orders to shoot rioters on sight.
There have been long-running tensions in Assam state between indigenous peoples and settlers.
Over the last two months, members of indigenous communities such as the Bodos have been targeting immigrant Muslims of Bengali descent, describing them as "illegal infiltrators" from Bangladesh, the BBC's Subir Bhaumik in Calcutta says.
The Muslim leaders say most of their people came to Assam before Bangladesh came into existence in 1971 and obtained Indian citizenship legally.
Helicopters are being used to spot movement of mobs in remote areas, Assam's police chief RN Mathur was quoted by news agency Reuters as saying.
Mr Mathur said an additional 500 federal police had been deployed in the state where hundreds of security forces were already trying to control the situation.
"It is not possible to have static security posts in each and every village, so we have intensified patrolling in remote areas," the agency quoted Himanta Biswa Sarma, a minister supervising security and relief measures, as saying.
More than 85,000 people have fled their homes
Meanwhile, violence has spread to Assam's western district of Chirang where three Muslims have been killed by armed Bodo tribespeople.
Among those killed was a pregnant woman.
One man injured in the clashes between Muslims and another tribe, the Rabhas, in the western district of Goalpara succumbed to his wounds on Tuesday.
A government spokesman said several relief camps had been opened in Udalguri and Darrang districts, mostly in school buildings, where tens of thousands of people had taken shelter.
Our correspondent says the Assam police have acted tough to quell the riots.
Clashes started late on Friday after news spread that some Muslims had stolen cattle from Bodo villages in Rowta area of Udalguri.
Rumours that Muslim militants had planted bombs and raised Pakistani flags added to the tension, local officials said.
Subsequently, several Muslim villages in Rowta were attacked and houses were set on fire.
The Muslims retaliated after the body of a Muslim man was found on Saturday morning.
Udalguri's head of administration and the police chief have been removed from their posts for failing to take prompt measures to curb the violence, officials said.
The state's Chief Minister Tarun Gogoi has appealed to all communities to refrain from any further violence and maintain calm.