Four more members of a youth soccer team have been rescued Monday from a flooded cave in Thailand, Reuters reported, bringing to eight those who've been evacuated out of 13 — 12 boys and their coach — trapped for more than two weeks.

A Reuters witness near the cave in the northern Chiang Rai province saw medical personnel carry four people out of the cave to waiting ambulances over the course of Monday, the second day of the rescue operation.

Four of 12 players plus their coach trapped in the cave were rescued Sunday, according to Chiang Rai provincial acting Gov. Narongsak Osatanakorn.

The boys were immediately taken to the hospital for evaluation after being trapped underground for nearly two weeks. Officials said the healthiest of the boys have been taken out first and the rescue operation is going better than expected, Independent.co reports. The next phase of the operation is expected to start in 10-20 hours.

The evacuation came several hours after 13 international cave diving experts and five Thai Navy SEALs entered the cave in an attempt to get the boys out one by one as they navigate through flooded and narrow tunnels. 

CNN notes: "To reach the boys, divers must navigate a series of dark, flooded tunnels for up to six hours. With the entire round trip taking roughly 11 hours to complete, it could be days before the entire group emerges."

It is estimated that the boys and their coach are 1.24 miles from the mouth of the cave and about 0.6 miles below the surface.

Depending on weather and water conditions, the entire operation to get all 13 members of the team out of the cave could last two to four days, according to army Maj. Gen. Chalongchai Chaiyakam.

The dozen boys between the ages of 11 and 16 are accompanied by their 25-year-old coach. They have been stuck in the cave since June 23 after heavy rains flooded the Tham Luang Nan Non caves in Chiang Rai, a popular tourist attraction in the region. They had been missing for 10 days before they were discovered.