Authorities have said the mission could take three or four days to complete.
But he could not confirm if all five would come out today. Ninety divers are involved in the rescue.
In the last 18 days, what began as a local search for the missing 13 turned into a complex rescue operation, involving hundreds of experts who flew in from around the world to help.
"Leaving here in case it may be useful in the future", he wrote, referring to the "mini-sub" which he has named after the team, the Wild Boars.
The boys and their coach went exploring in the massive Tham Luang Nang Non cave on June 23 after a soccer practice, and were cut off when a rainstorm flooded the cave.
A stretcher carrying what is believed to be a fifth boy rescued from a cave in northern Thailand.
It was not immediately clear on Monday whether more rain overnight had affected water levels inside the cave.
Hundreds of spectators and journalists have gathered in the area around the cave, hoping for news that the boys and their coach would emerge safely. Monsoon flooding blocked off their escape and prevented rescuers from finding them for nearly 10 days. The four unidentified boys were the second batch to be retrieved in as many days by ace rescue divers from a deep and winding cave in the northernmost reaches of Thailand.
The boys are being guided out of the cave by two divers with oxygen tanks.
On Sunday, officials waited until several hours after the rescued boys had been transported to hospitals to announce their rescue.
The rescue mission has been a huge operation, led by the Royal Thai Navy's SEAL unit, and supported by a cast of hundreds.
ANP leader among three others killed in Peshawar blast
According to the reports, the blast took place when Haroon reached the site for the public meeting in Yakatoot area of KP capital. Haroon Bilour was ANP candidate for a provincial seat for the upcoming general elections to be held on July 25 general.
Four other members of the team were successfully extracted Sunday.
Unconfirmed reports that the boys' coach, Ekapol Chanthawong, 25, was among the first four to be evacuated because of the poor state of his health, were dismissed on Monday.
Their escape led to an explosion of jubilation on social media in Thailand as the rescued boys were rushed to hospital.
Rescue mission chief Narongsak Osottanakorn said it had resumed, with divers re-entering the cave at 11am local time (4pm NZT). I've told Yod to get ready to take me out for fried chicken.
And although the four had been rescued, there were concerns they may have contracted an illness while in the cave, Narongsak said on Monday.
The only way to bring the boys and their coach out of the cave is by navigating dark and tight passageways filled with muddy water and strong currents, as well as oxygen-depleted air. That brought the total number of boys rescued to five.
Another video from Thai PBS showed an ambulance arriving at a hospital in the city of Chiang Rai, near the cave network. Prime Minister Prayuth Chan-ocha was visiting all eight in the nearby hospital that they were helicoptered to, he said.
The trapped boys have been divided into groups. "We've used all the oxygen", Osatanakorn told reporters. A family member told CNN Monday that they hadn't been told which boys had been pulled out, and who is still trapped in the cave.
"In the next few hours we will have good news". One was that it was unknown how safe and dry the area where they had taken shelter would stay as Thailand's rainy season, which lasts until at least late October, picks up pace.
And Gianna Infantino, the president of Federation Internationale de Football Association, soccer's governing body, has invited the boys to the World Cup final in Moscow on Sunday.
Next is Hannah Carter , an old friend of Kate Middleton's from Marlborough College who is married to Robert Carter. Accompanying the duchess was Prince William , who held Princess Charlotte and Prince George by the hand.
Even so, when May appeared in parliament on Monday afternoon, she didn't look like a woman who was facing an existential crisis. May's supporters are now reported to be anxious that more ministers could go and a no-confidence vote could be triggered.
Most of the protesters at the Malheur site were acquitted of charges the government brought against them. The federal sentencing of Dwight and Steven Hammond for arson sparked the anti-government occupation.
The three-term Republican says the Senate has gotten in the bad habit of treating people as "innocent until nominated". Senate Minority Leader Chuck Schumer promised to opposed Judge Kavanaugh's nomination with everything he has.
The Daily Mail report Chelsea are keen to allow Kenedy more first-team opportunities and Newcastle can provide that opportunity. He has made just five Premier League starts for Chelsea since moving to Stamford Bridge from Fluminense three years ago.
She paired the dress with a matching fascinator by Stephen Jones , gold-and-diamond Cartier earrings, and nude heels. Harry and Meghan later joined royals at a Buckingham Palace reception to mark the centenary of the Royal Air Force.
After Trump's "working visit" - as opposed to a formal state visit - was announced in April, the effort went into overdrive. The president is scheduled to meet with British Prime Minister Theresa May and Queen Elizabeth during his visit.
The 27-year-old Algeria global will join the Manchester side after Leicester City accepted a Club-record fee for the transfer. Riyad Mahrez is reportedly undergoing a medical at Manchester City ahead of a move from Leicester City .
Marouane Fellaini , who has oft-partnered Pogba in the United midfield, will now be looking to stop the powerful Frenchman. This fixture is one of the matches that could easily have been the "Final" of this 2018 World Cup in Russian Federation .
The 40-year-old 2006 World Cup victor joins the big-spending Parisian side days after his contract with Juventus ended in June. He would become the first signing under the new PSG manager, Thomas Tuchel, who replaced now-Arsenal boss Unai Emery.
France reach 2018 World Cup final, beat Belgium 1-0
Benjamin Pavard went closer with a shot Courtois saved with his outstretched foot after Mbappe had hypnotized the Belgian defense. It was one of Dembele's last acts as Dries Mertens came on for the midfielder as Belgium chased an equaliser.
Trump announcing his SCOTUS nominee in prime time
Republicans changed the Senate's rules a year ago to allow them to confirm a Supreme Court justice with a simple majority vote. Court of Appeals for the 3rd Circuit, where he served at one time with Trump's sister, Judge Maryanne Trump Barry.
Harry and Meghan due in Dublin for two-day visit
In 2011, the Queen became the first British monarch to visit Ireland since her grandfather George V's visit in 1911. They are due to meet Taoiseach (Irish prime minister) Leo Varadkar and Irish President Michael D Higgins.
Justin Bieber 'engaged to Hailey Baldwin'
The post was captioned: "well my friend just met justin bieber and hailey baldwin in the bahamas and she is wearing a ring". Dating rumors started to fly in 2014, but Bieber shut down speculation with a photo captioned: " People are insane .
Cristiano Ronaldo agrees to join Juventus
Real Madrid has won my heart and that of my family and it is because of that, now more than ever, I would like to say thank you. He is also a five-time world player of the year, a record he shares with his eternal rival, Argentine talisman Lionel Messi .