Cave divers in Thailand are poised to restart the high-risk operation to extract the remaining eight boys and their football coach from a vast flooded cave system.
Four boys were brought safely out of the cave on Sunday.
But the mission was paused overnight for air tanks to be replaced.
The boys became trapped in the cave on 23 June after heavy rains caused flooding, but were found alive last week by divers.
Rescuers decided to go ahead with the hazardous operation to free them because of fears that waters would rise again.
Activity at the dive site early on Monday suggests that the operation may have resumed or be about to resume. But there has been no confirmation.
At least seven ambulances have driven towards the cave entrance.
The BBC’s Jonathan Head says this is a tightly controlled operation, and the identities of the boys who got out are being kept secret – it is not clear whether even their families have been told.
■ How risky is the Thai boys rescue?
■ The operation in pictures
Rescuers took advantage of a break in the rain on Sunday to launch the mission earlier than some expected.
The first stage of the mission ran “smoothly” and the rescued boys were in “good health”, according to the Thai authorities.
But with heavy rainfall overnight and more forecast for the coming days, divers will need to work quickly to free those still trapped. On Saturday, Narongsak Osottanakorn, governor of the Chiang Rai province, said that teams had a three to four-day window to carry out their operation.
How are the boys being moved?
A team of 90 expert divers – 40 from Thailand and 50 from overseas – has been working in the cave system.
They have been guiding the boys through darkness and submerged passageways towards the mouth of the Tham Luang cave system.
Getting to and from where the boys are has been an exhausting round trip, even for the experienced divers.
■ ‘I am dying to see him. I miss my son’
■ Letters of love from trapped Thai boys
The process includes a mixture of walking, wading, climbing and diving along guide ropes already in place.
Wearing full-face masks, which are easier for novice divers than traditional respirators, each boy is being accompanied by two divers, who also carry his air supply.
The toughest part is about halfway out at a section named “T-Junction”, which is so tight the divers have to take off their air tanks to get through.
Beyond that a cavern – called Chamber 3 – has been turned into a forward base for the divers.
There the boys can rest before making the last, easier walk out to the entrance. They are then taken to hospital in Chiang Rai.
In an indication of how dangerous the journey can be, a former Thai navy diver died in the caves on Friday. Saman Gunan was returning from a mission to provide the group with air tanks when he ran out of oxygen.
He lost consciousness and could not be revived. His colleagues said they would “not let the sacrifice of our friend go to waste”.
Sense of remaining unease
BBC’s Nick Beake at the scene
This is a hugely high-profile rescue attempt and Thailand knows the world is watching. It has embarked on a dangerous option but believes it’s the best for bringing the group out alive.
It has assembled a team of internationally renowned divers and so far their expertise has brought four boys – thought to be the weakest – back to their families.
But the relief of those mums and dads will be tempered by the knowledge that nine other families face an anxious wait for the turn of their loved ones to be shepherded through the narrow and murky corridors of the Tham Luang cave complex.
As one diving expert put it to me, when underwater cave rescues go wrong, they go wrong in a big way. So despite this promising start, there is a sense of unease here in Chiang Rai. But the overriding impression from the rescuers is a clear focus and unshakable resolve to finish the job.
Who are the boys and their coach?
■ Chanin Vibulrungruang, 11 (Nickname: Titan) – started playing football aged seven
■ Panumas Sangdee, 13 (Nickname: Mig), wrote to his parents: “The Navy Seals are taking good care of me”
■ Duganpet Promtep, 13 (Nickname: Dom) – captain of the Wild Boars, reportedly scouted by several Thai professional clubs
■ Somepong Jaiwong, 13 (nickname: Pong) – reportedly dreams of playing for the Thai national team
■ Mongkol Booneiam, 13 (nickname: Mark) – described by his teacher as a “very respectful and good child”
■ Nattawut Takamrong, 14 (nickname: Tern) – told his parents not to worry about him
■ Ekarat Wongsukchan, 14 (nickname: Bew) – promised his mother he would help her at the shop once he was rescued
■ Adul Sam-on, 14 – member of a volleyball team that came second in a North Thailand-wide tournament
■ Prajak Sutham, 15 (nickname: Note) – described by family friends as a “smart, quiet guy”
■ Pipat Pho, 15 (nickname: Nick) – wrote in his letter he wanted his parents to take him for barbecued food once rescued
■ Pornchai Kamluang, 16 (nickname: Tee) – told his parents “don’t worry, I’m very happy”
■ Peerapat Sompiangjai, 17 (nickname: Night) – it was his birthday the day the boys went missing, and his parents have told him they are still waiting to hold his birthday party
■ Assistant coach Ekapol Chantawong (nickname Ake), 25 – apologised in his letter to the parents, but they replied that they did not blame him
How did the group get there?
The boys were found inside the cave by British rescue divers a week ago, about 4km (2.5 miles) from the cave mouth.
Aged between 11 and 17, they belong to a football club called the Wild Boars, and became trapped during an excursion with their coach.
It took nine days to find them in the underground network’s dark depths.
Race against the rain
Officials had originally thought the group might have to stay where they were until the rainy season ended – and that could have meant months underground.
They had also been exploring whether they could drill down into the cave, as well as scouring the mountainside for another way in.
But with the rainy season just beginning, it has become clear that the flooding which originally trapped the boys will only get worse in the coming days.
Rescuers have been desperately pumping water out of the cave, and Mr Narongsak said on Sunday that water levels inside were at their lowest levels so far.
Source: BBC news
