MAE SAI, Thailand (CBSNews/AP) — Early Sunday in Thailand, officials said the operation to rescue a soccer team stranded in a flooded cave may begin soon if torrential rains hold off.

Officials appear to be close to launching their rescue mission, CBS News reports. However, the 12 boys, ages 11 to 16, are weak from being stranded for more than two weeks and are still learning how to use the dive equipment they may need to escape.

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Narongsak Osottanakorn, head of the operation, said crews will do everything they can to minimize the risk. They have been pumping water from the cave to lower the water level, so the boys can escape without having to swim underwater.

The dangerous journey killed a trained Navy SEAL on Friday, who passed out underwater while delivery oxygen tanks inside the cave. Three workers were injured in a fall at the site on Saturday.

The oxygen tanks are needed because levels are dropping down to an alarming 15 percent. Crews are working to install a three-mile long oxygen tube and have delivered additional tanks to the boys. They are considering drilling a hole into the mountain to reach them if a water escape proves too dangerous.

Meanwhile, the 25-year-old soccer coach who brought the boys into the cave issued a letter apologizing to their parents.

“To the parents of all the kids, right now the kids are all fine, the crew are taking good care. I promise I will care for the kids as best as possible. I want to say thanks for all the support and I want to apologize to the parents,” he wrote.

The boys also wrote letters to their families saying, “I love you, mom and dad… Don’t worry, we are safe now,” “When I come out, we will go eat fried chicken,” “I miss everybody,” and “Don’t forget to arrange a birthday party for me.”

CBS News spoke with a 15-year-old boy who’s on the soccer team but missed the cave trip, because his parents needed his motorbike.

“I feel bad, like I abandoned them,” he said. “I should have stopped them from going inside.”

The boys, ages 11-16, and their 25-year-old became stranded when they went exploring in the cave after a practice game. Monsoon flooding cut off their escape and prevented rescuers from finding them for almost 10 days.