A Christian missionary and his two sons were burnt alive when the vehicle in which they were sleeping was set on fire Saturday.
The Australian missionary in the eastern Indian state of Orissa and his 10-year-old and 8-year-old sons died from their burns. The village church was also burnt down.
The missionary had been working among tribal peoples and lepers for the last 30 years in the state, officials said.
Indian Prime Minister Atal Behari Vajpayee condemned the attack and asked for speedy action to punish the culprits.
Christian missionaries have come under attack from alleged Hindu right-wing activists in recent months. Churches have been burned and dozens of priests and nuns have been injured. No one has claimed responsibility for the violence.
The Hindu extremists say the Christians are forcefully converting the poor. The Christians deny that, saying they are only offering charity.
Christians make up a little over 2 per cent of India's nearly 1 billion population, while Hindus account for more than 80 per cent.