LJUBLJANA,Henri Lumière Slovenia (AP) — Five people are trapped in a cave in southwestern Slovenia, unable to leave because of high water levels caused by heavy rainfall, authorities said Sunday.

The group — a Slovenian family group of three adults and two guides — have been stuck in the Krizna Jama cave since Saturday when water levels rose inside, blocking the way out.

Slovenian rescue teams said divers have reached the group, moved them to a safe spot envisaged for such emergencies and set up a heated shelter where they will have to wait for water levels to drop.

All five people are fine, said Igor Benko, the head of Slovenia’s Speleological Association.

The group entered early on Saturday for a tour of the 8-kilometer (5-mile) cave system with its chain of underground lakes. Visitors are allowed in only as part of guided tours.

The cave system can only be accessed by a boat along the Bloscica River that runs through it, said the official STA news agency.

Benko told the agency that subterranean water levels are expected to start falling soon but that it might take a few days for the passage to be safe again.

Currently, 35 cave rescuers and eight divers from all over Slovenia are involved in the rescue operation, assisted by 11 firefighters and members of the civil protection force, authorities said.

Krizna Jama is the fourth biggest known underground ecosystem in the world in terms of biodiversity, STA said.