The boys, aged 11-15, are believed to have entered the Tham Luang Nang Non cave in Chiang Rai province with their 25-year-old coach late Saturday afternoon. Instead, they turned to the Sirikorn rescue team in Chiang Rai for help. A mother who reported her son never returned from soccer practice that day set off the search.
The rescue workers of the Siam Ruanjai Mae Sai unit and related agencies had searched for the young footballers of Tambon Pong Pha after receiving a report at 7pm that they had gone missing in the cave.
Heavy monsoon rains have hit the region in recent days, causing the cave to rapidly fill with water, and bicycles and shoes belonging to the boys were found soon afterwards at the cave's entrance.
Diving equipment has been prepared to facilitate the children's evacuation, Mr Pasakorn said.
According to the Bangkok Post newspaper, visitors must cross a small stream to enter Tham Luang Nang Non, making it inaccessible if the stream floods.
"We are still searching right now", Chote Narin, an officer at Mae Sai district police station, said on Monday.
Navy SEAL divers were trying to reach a large chamber deep inside the cave complex where officials thought the students might be.
A navy commander overseeing the search said he was hopeful they would be found. "I believe they're all still alive but they might be exhausted". After that area, the cave splits off into different directions, including several that lead to other chambers, pools of water or places with high "avens", shafts that reach the surface. Murky floodwaters were also hampering the effort.
People wanting to explore the cave are meant to get permission. After they resumed the search on Sunday morning, a source in the rescue unit claimed the group had been found but they could not come out as the water level was unsafe. "We hope they will be rescued soon", a relative of the group told The Nation.