YELLOWSTONE NATIONAL PARK, Wyo. (AP) — Search and rescue teams are continuing to search Yellowstone National Park for a seasonal worker from China who went missing July 23 while swimming.

The park says that 12 to 18 searchers as well as two teams of dogs and helicopters have continued to search for 21-year-old Feiyang "Isaac" Xiang. The seasonal park concessionaire is believed to be in a 6-mile segment of the Yellowstone River near its confluence with Hellroaring Creek.

Xiang of the Hubei province disappeared while swimming with friends in the river after the current pulled him away from the shore.

The area of the Yellowstone where Xiang is thought to be is known to have deep pools, rapids and rocks.

No signs of Xiang have been found.