BRASILIA, Brazil (AP) _ Settlers hunting with rifles in the western Amazon jungle shot at Indians believed to be from among the world's largest group of uncontacted tribes, killing one of them, authorities said.

Officers in Acre state discovered the man's body last week in dense jungle in the Upper Tarauaca River Indigenous Area, near the remote settlement of Jordao, police said Monday. The area is some 1,600 miles west of Brasilia.

``Fifteen settlers said they were hunting when they came across a group of nine warrior Indians armed with bows and arrows. They shot at them to head off an expected attack,'' said Glorivan Bernardes, federal police chief in Acre. ``The Indians didn't retaliate and fled into the jungle.''

Up to 1,000 Indians, all of them uncontacted and from up to four unnamed tribes, are believed to live in the Upper Tarauaca Indigenous Area, a 56,800-acre tract of jungle informally recognized as Indian land, said Antonio Pereira Neto, the Federal Indian Bureau chief in Acre. Brazil is in the process of declaring it a reservation.

``As far as we know, these Indians form the largest group of documented uncontacted tribes in the world,'' he said.

Neto said there is an Indian village less than six miles from where the body was found. The village _ containing seven Indian houses surrounded by banana, manioc and cotton fields _ and three other similar villages in the area are known to the Indian Bureau only from aerial photographs.

Bernardes said the shooting incident occurred in June, but police only discovered the body _ riddled with bullets and in an advanced state of decay _ last week after the Federal Indian Bureau reported rumors about the confrontation.

Officers were searching Monday for Jose Lourenco Da Silva, a rubber tapper who lives in Jordao, on suspicion of murder. Settlers involved in the attack told police he was the one who shot and killed the Indian, Bernardes said.

It was not yet known how many of the other settlers fired shots at the Indians. Bernardes said Da Silva and others could be charged with murder, pending an autopsy of the Indian's body and the results of continuing investigations in Jordao.

Little is known about the Indians in the area. They are tall, with close-cropped hair. They hunt with bows, arrows and stolen guns. Those few details are based on fleeting encounters between the Indians and some of the 5,000 hunters, loggers and rubber tappers who live in Jordao and regularly pass near the tribal villages to hunt and chop wood.

In the past three years, three settlers, including a young woman, were killed by Indians near Jordao, police said. There have also been reports of Indians being killed in recent years. Until now, none had been confirmed.

Brazil's Indian policy calls for the total isolation of uncontacted tribes to protect them from the encroachment of civilization, according to the Indian Bureau. Indian Bureau officials said they hope the death of the Indian will speed up the process of demarcation of the Upper Tarauaca Indian Reservation, which will make it illegal for settlers to live, hunt or log on Indian lands.

The reservation is still awaiting approval by the government. Depending on how it is drawn, the non-Indian residents of Jordao could be resettled to another area.

``What happened is a terrible example of the great violence that threatens the indians everyday,'' Neto said. ``We should be thankful that these Indians still exist and protect them as part of this planet's heritage.''