An emergency team carries a stretcher believed to be carrying one of the rescued boys from the flooded cave to a waiting helicopter in Mae Sai, northern Thailand. Picture: Big Krean via AP
An emergency team carries a stretcher believed to be carrying one of the rescued boys from the flooded cave to a waiting helicopter in Mae Sai, northern Thailand. Picture: Big Krean via AP
Two helicopters wait near the cave for more evacuations of the boys and their soccer coach who have been trapped since June 23, in Mae Sai, Chiang Rai province, northern Thailand. Picture: Sakchai Lalit/AP
Two helicopters wait near the cave for more evacuations of the boys and their soccer coach who have been trapped since June 23, in Mae Sai, Chiang Rai province, northern Thailand. Picture: Sakchai Lalit/AP
A Thai well wisher puts a poster to pray for boys and their soccer coach who have been trapped since June 23, in Mae Sai, northern Thailand. Picture: Sakchai Lalit/AP
A Thai well wisher puts a poster to pray for boys and their soccer coach who have been trapped since June 23, in Mae Sai, northern Thailand. Picture: Sakchai Lalit/AP
A well-wisher puts up a poster with a prayer for a youth soccer team and their coach who have been trapped since June 23, in Mae Sai. The poster reads " Take Wild Boars back home." Picture: Sakchai Lalit/AP
A well-wisher puts up a poster with a prayer for a youth soccer team and their coach who have been trapped since June 23, in Mae Sai. The poster reads " Take Wild Boars back home." Picture: Sakchai Lalit/AP
Two ambulances arrive near the cave to wait for more evacuations of the boys and their soccer coach who have been trapped since June 23. Picture: Sakchai Lalit/AP
Two ambulances arrive near the cave to wait for more evacuations of the boys and their soccer coach who have been trapped since June 23. Picture: Sakchai Lalit/AP
A helicopter waits near the cave for more evacuations of the boys and their soccer coach who have been trapped since June 23, in Mae Sai, Chiang Rai province. Picture: Sakchai Lalit/AP
A helicopter waits near the cave for more evacuations of the boys and their soccer coach who have been trapped since June 23, in Mae Sai, Chiang Rai province. Picture: Sakchai Lalit/AP
This frame grab from video tweeted by Elon Musk shows a "tiny kid-sized submarine" being tested in a pool at Palisades Charter High School, in Pacific Palisades, California. Musk's Space X rocket company tested the submarine that could potentially help rescue the remaining children and their coach trapped in a flooded cave in Thailand. Picture:  Elon Musk via AP
This frame grab from video tweeted by Elon Musk shows a "tiny kid-sized submarine" being tested in a pool at Palisades Charter High School, in Pacific Palisades, California. Musk's Space X rocket company tested the submarine that could potentially help rescue the remaining children and their coach trapped in a flooded cave in Thailand. Picture: Elon Musk via AP

Mae Sai, Thailand - Thai authorities said the second phase of the operation to rescue a youth soccer team trapped in a flooded cave was underway Monday, a day after four boys were pulled from the complex after more than two weeks underground.

Chiang Rai acting Gov. Narongsak Osatanakorn said the second phase began at 11 a.m. and authorities "hope to hear good news in the next few hours." Nine people remain trapped in the cave.

Authorities have been rushing to extract the boys, ages 11-16, and their coach from the cave as monsoon rains bore down on the mountainous region in far northern Chiang Rai province. Authorities said heavy downpours overnight did not raise water levels in the cave, where workers continue to pump water out.

The four boys pulled from the cave Sunday in an urgent and dangerous operation that involved them diving through the cave's tight and twisting passages were in good health. Still, they were undergoing medical checks in a hospital and were not yet allowed close contact with relatives due to fear of infections, who were able to see them through a glass partition.

Interior Minister Anupong Paojinda had said early Monday that the same divers who took part in Sunday's rescue would return to extricate the others as they know the cave conditions and what to do. He had said fresh air tanks needed to be laid along the underwater route.

Prime Minister Prayuth Chan-ocha was scheduled to visit the site later Monday.

AP