A search is underway to rescue 12 teenage soccer players and their coach who are thought to be trapped in a cave in northern Thailand.
Investigators believe the team, which has been missing since Saturday, crawled into the Tham Luang Nang Non Cave through a narrow 15-meter long channel.
Rising waters then blocked the path, which is about as wide as a single person, leaving the group stuck inside the cave network, Kamolchai Kotcha, an official with Thailand's national parks authority, told CNN.
"We have been working almost 24 hours but there are many limitations, the caves are pitch dark and very low level of oxygen in some areas, and scattering rains just made our task more difficult," said Kotcha.
Park officials, local police and 17 members of the SEAL diving team from the Royal Thai Navy have been deployed to assist in the search and rescue efforts. The divers entered the cave chamber on Monday morning to look for the missing group.
A post on the Thai Royal Navy SEAL page at 4 p.m. local time (5 a.m. ET) stated: "It is still drizzling (and) water level is rising. Handprints were found around cave's wall. But we still cannot locate the kids. Rescue operation continues."
An image posted on the Facebook page said that SEAL divers have to dive to a depth of five meters to access the main chamber, where the missing people are believed to be located.
The 13 people, all males from Chiang Rai, have been missing since 1 p.m. local time Saturday, when a park officer spotted something amiss -- bicycles parked idly by the entrance to the cave, despite it being off-limits.
The caves, which authorities estimate are up to 3 kilometers long in parts, are located in a well-known spot for local explorers and tourists in the northern province of Chiang Rai's Mae Sai District.
Northern Thailand is famous for its remote and untouched caves, which draw visitors from around the world.