Rescue workers scaled down an Amazon mountain Sunday in search of five people feared dead after their plane crashed a week ago, a U.S.-based missionary group said.

Two Americans, two Canadians and a Venezuelan Indian affiliated with the religious group were on board the Cessna 207 that slammed into a mountain 190 miles southeast of Puerto Ayacucho on Monday.

A rescue team, including a former U.S. Navy SEAL who is now a missionary, landed on the mountaintop Saturday and were inching down it Sunday, said Jim Bou, a spokesman for the Sanford, Fla.-based New Tribes missionaries.

By late Sunday afternoon, there was no word on whether they had reached the crash site, which pilots have spotted during several flyovers.

Clouds, wind and smoke from wildfires burning out of control in neighboring Brazil prevented rescue workers from landing on the mountaintop earlier. Two other teams that were trying to climb the mountain from its base were forced to give up.