North Sentinel Island representatives killed the US tourist, AFP reported.
Seven people arrested as they brought American tourist John Chau, 27, to the island.
According to them, the tribe attack an American with a bow and arrow and then dug him in the sand on the beach.
Contact with several tribes on the islands is illegal in a bid to protect their indigenous way of life.
The population of the tribe was estimated at 40 people in 2011. They are known for avoiding contact with the outside world.