Rescuers say more debris fell overnight, and the body is in the back of the cave, buried by rock and ice. Five people were injured in the collapse and are expected to survive.

“Right now they are looking at every possible option,” Snohomish County sheriff’s spokeswoman Shari Ireton said at a news conference Tuesday morning. “Anybody who steps in it is at risk.”

Signs warn visitors of the hazards from ice and rock at the Big Four Ice Caves, a popular hiking destination about 70 miles northeast of Seattle. Warm weather has made the caves unstable this season, and the ice caves have been closed until further notice. Temperatures in the area Monday were in the 80s.

Thousands of visitors walk a one-mile trail to reach the ice caves, which are the lowest elevation permanent snow and ice patch in the United States outside of Alaska. People go to the area surrounding the caves for the spectacular mountain scenery and to escape the summer heat.

The caves are formed by avalanches that cascade down from nearby the 6,135-foot Big Four Mountain during the winter and spring. Most years, one or more caves form as the ice melts. The U.S. Forest Service has warned hikers that the ice caves were dangerous due to unseasonably warm weather. Visitors were urged to stay on the trail, not to enter the cave and to be cautious in the area, which is prone to falling rocks and ice.

That hasn’t kept hikers out of the caves. A different section came tumbling down on Sunday, but none of the hikers inside were injured.

“It was a very terrifying moment,” said Sara Soleimani, an avid ice climber who filmed Sunday’s partial cave collapse and said she heard ice cracking just a few seconds before a chunk of the cave sheared off.

“I was shaking for about 10 minutes after,” said Soleimani, 28, of Long Beach, California.

Scott Pattee, a water supply specialist with the Natural Resources Conservation Service, said this year’s snowpack has been almost non-existent, and with so little snow, there have been fewer avalanches to feed the ice caves.

“It doesn’t surprise me that something like that happens. Ice melts when it’s warm,” he said.

The five people injured are recovering. A 25-year-old man in intensive care is in serious condition, Harborview Medical Center spokeswoman Susan Gregg said, while a 35-year-old man is in satisfactory condition and a 35-year-old woman was treated and released. Two minors also were treated and released from another hospital.

Chloe Jakubowski, 18, told The Seattle Times that she and a handful of others were in the cave Monday when she heard a loud crack, then ice and debris cascaded down. She said she covered her head with her arms and crouched behind a giant rock of ice.

When she stood up, a woman next to her lay unconscious. Others nearby suffered cuts and broken bones.

She said she saw the warning signs outside but went in anyway, because she didn’t see anything that seemed to point toward a collapse and others were already in the cave.

Jakubowski told the newspaper that she and three friends drove about 15 miles to a pay phone to alert emergency crews. There was no cellphone service at the remote cave site.

The first emergency call came in at 5:38 p.m., and the collapse probably happened about 45 minutes earlier, Ireton said.

There have been deaths at the caves before. In July 2010, an 11-year-old girl was killed outside the caves by a bouncing chunk of ice.