The second phase of the operation to rescue eight boys and their soccer coach who remain trapped in a flooded cave in Thailand is underway Monday.

Four boys were rescued on Sunday.

They're currently recovering at a hospital in Thailand.

Officials have described their condition as "not that bad."

Rescue efforts had stopped temporarily until new oxygen tanks could be placed along the escape route, which is partially under water.

The soccer team became trapped inside the cave when it flooded on June 23.

There was no measurable rainfall in northern Thailand up until Sunday, but when it started up again, it caused a major concern for the safety of the team and forecasters say it's expected to rain heavily all this week.

Narongsak Osottanakorn, governor of Chiang Rai province, said "This is what we have been racing against since day one. We have to do all we can, even though it is hard to fight the force of nature."