SALT LAKE CITY - A pair of black bears raided two separate camps of rafting parties, biting one camper late Wednesday in remote Desolation Canyon on the Green River, the site of a similar attack last July.

The unidentified male victim, a member of an organized rafting trip, suffered only minor injuries, authorities said.

He remained on the river Thursday, floating to a takeout 65 miles downstream near Green River, Utah, that authorities estimated could take his group two days to reach.

The attack about 120 miles southeast of Salt Lake City occurred at 10:45 p.m. Wednesday, said Bruce Palmer, marketing director for the National Outdoor Leadership School in Lander, Wyo., which received word of the attack by satellite telephone.

Palmer said two bears came into a school camp and "stole some food and tore up some tents. Our students and instructors got up and banged some pots, and the bears headed south to another camp. That's where the person was attacked."

The victim was part of another outfitter's group.

Two trappers for the Utah Department of Agriculture flew to the site of the attack Thursday to set snares in an effort to capture and kill both bears and post warnings advising other rafting groups to avoid the camp.

"It's going to be a priority for us to get these bears caught," said Derris Jones, regional supervisor for the Utah Division of Wildlife Resources.

Because bears are solitary animals, Jones said it would be highly unusual for two unrelated adult bears to spend time together outside of mating season raiding camps. He guessed the two bears were siblings, yearlings kicked out of a den by their mother last fall, who picked up a habit of scouring campsites for food.

"When a bear shows no fear of humans, we remove that bear. This is one of those incidents. We're going to try to remove the bears, but it's wild country and we may not find them," Jones said.

The victim suffered a puncture wound to a thigh and scratches on his abdomen, said Ruth McCord, spokeswoman for the Bureau of Land Management in Price, Utah.

Jones said the victim may have required only a tetanus shot, which his outfitter could have provided. If his condition were more serious, the group would have used a satellite phone to call for a medical helicopter, he said.

Black bears are frequently seen on both sides of the Green River in Desolation Canyon. The attack was similar to one that occurred last July along the same stretch of river.

In that case, a bear grabbed Nick Greeve, 18, of West Linn, Ore., by the head and neck in his sleeping bag. Greeve was treated at a hospital for puncture wounds and lacerations.

Other campers in the rafting party of 20 chased the bear away, which wildlife officials were unable to find.