One person has died and two others were still missing a day after an ice cave collapsed in southeast Iceland while a tour group was visiting the area, police said Monday.

A group of 25 people of "several nationalities" were on an organised tour of the glacier Breidamerkurjokull together with a guide, when the cave collapsed, police said in a statement.

Police said that four people got stuck under the ice and two of them had been found.

On Sunday, Sudurland police said the two people recovered were seriously injured, but added in a later statement early Monday that one of them had been "pronounced dead at the scene."

The other person was transported to a hospital by helicopter and was in a "stable" condition.

Rescue services began a search operation for the two missing Sunday and were continuing the search on Monday.

"A large number of rescuers and responders have taken part in the operation," police said, adding that the conditions were "difficult."

Authorities decided to temporarily suspend the search on Sunday evening once it became too dark and it was no longer considered safe.

The glacier where the accident happened is near the glacial lagoon Jokulsarlon, one of Iceland's more popular tourist destinations.