By Joe Holden

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PHILADELPHIA (CBS) — The rescue effort being watched around the world was suspended once the sun went down, but Thai officials say the search has resumed.

In Thailand, rescuers are gearing up for the next phase of their effort to free a youth soccer team trapped in a flooded mountain cave.

On Sunday, divers escorted four of the 12 boys back to the surface, a two and a half mile journey through a series of dark and flooded tunnels.

“You can’t make a horror movie that would even compare,” said Anmar Mirza, National Coordinator of the rescue mission. “This is the most scary situation that a person could go through, especially for people who aren’t used to the environment that they are in and might not have any knowledge of what is happening.”

After the four emerged from the cave, they were rushed to the hospital in ambulances.

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Officials in charge of the operation said they’re hoping to bring another group of boys out by Monday or Tuesday.

“The good news is that the first phase was successful,” said Mirza. “So they had an opportunity to show it works. It’s still dangerous but it’s much better odds for the remaining kids to come out now because of those initial ones.”

Before they attempt another rescue, the dive teams have to refill their oxygen tanks and replenish the supplies along the route inside the cave.

President Donald Trump tweeted this morning, “The U.S. is working very closely with the Government of Thailand to help get all of the children out of the cave and to safety. Very brave and talented people!”

Two divers are assigned to each boy, helping them carefully navigate out of the cave.