Ice caves popular with hikers north-east of Seattle partially collapsed, killing one person and leaving at least four others injured, officials said.

Monday's collapse came after authorities warned that the caves were especially dangerous because of warming temperatures.

The person who died remained buried under the debris at the Big Four Ice Caves east of Verlot, Snohomish County sheriff's spokeswoman Shari Ireton said late Monday night. The recovery effort was suspended at nightfall.

All victims were believed accounted for, Ireton said.

Three of the injured, including a 25-year-old man in critical condition, were airlifted to a Seattle trauma center. They included a seriously injured 35-year-old man and a 35-year-old woman in satisfactory condition, hospital spokeswoman Susan Gregg said. Their injuries included cuts and leg and pelvis fractures.

A fourth person, a juvenile girl with minor injuries, was sent to an Everett, Washington, hospital, Ireton said. Providence regional medical center in Everett also expected a second patient, spokeswoman Diane Torrance said late Monday night.