In the first detailed mission report to be published, rescuers say they heard screams and fighting for dry land.

The rescue operation to free the last of the 12 boys and their football coach from a Thailand cave could have been a disaster, divers have revealed, with water pumps draining the area failing just hours after the last boy had been evacuated.

Divers and rescue workers were still more than 1.5km inside the cave clearing up equipment when the main pump failed, leading water levels to rapidly increase, three Australian divers involved in the operation told the Guardian on Wednesday, in the first detailed account of the mission to be published.

The trio, stationed at “chamber three”, a base inside the cave, said they heard screaming and saw a rush of head torches from deeper inside the tunnel as workers scrambled to reach dry ground.

“The screams started coming because the main pumps failed and the water started rising,” said one of the divers, speaking anonymously because he is not authorised to comment.

“All these headlights start coming over the hill and the water was coming … It was noticeably rising.”

The remaining 100 workers inside the cave frantically rushed to the exit and were out less than an hour later, including the last three Thai navy Seals and medic who had spent much of the past week keeping vigil with the trapped boys.

The boys of the Wild Boar football team were brought out in three daring rescue operations starting on Sunday morning. An elite team of 19 divers were involved in ferrying the boys and their 25-year-old coach the approximately 3.2km path from the muddy slope where they had been sheltering to the outside world.

The first four emerged on Sunday, the next four on Monday and then the final five about 8pm local time on Tuesday evening. The operation required the boys to learn to breathe using scuba masks and to traverse narrow, jagged tunnels.

During the final mission, as the three Seals and doctor were passed up the human chain of rescuers that had formed inside the cave, each section began cheering and applauding. The rescuers compared it to a joyful Mexican wave that continued until the entrance.

The rescuers in the daisy chain spent more than eight hours a day standing on a tiny patch of wet, muddy ground waiting for their turn to pass the boys along the treacherous path. “If one of those people doesn’t do their jobs properly, the stretcher falls,” one diver said.

The journey from chamber three to the cave entrance took about four to five hours initially, but was reduced to less than an hour after a week of draining and clearing the mud path using shovels.

The 12 boys, who wore diving cylinders and were each tethered to an adult diver, had to submerge themselves for much of the journey but were carried on bright red Sked stretchers whenever they entered patches of dry ground. Each one left the cave on these stretchers still wearing their breathing masks.

Much of last week was spent clearing the 1.5km path from chamber three to the entrance. When the Australian divers arrived on 30 June, “the complexity and scale [of the cave] was unknown”, said commander Glen McEwen, of the Australian federal police at a briefing on Wednesday.

The Australian divers, carrying 46kg of diving gear, were among the teams ferrying radios, air cylinders and other equipment into the third chamber.

Six Australian police divers and one navy diver spent 75 hours in that cave, McEwen said, “moving approximately 20 tonnes of equipment through the caving system”.

The equipment included industrial-size pumps, oxygen and air tanks, medical supplies and food.

“They did dive and as you can appreciate at that time there were no pumps in operation,” McEwen said. “So it was an unfriendly operation, it was narrow, it was flooded.”

The Australians were unable to go further because their gear was too large: going beyond chamber three required passing through a hole less than a metre wide.

The specialist cave divers and the boys wore smaller equipment such as rebreathers and tanks at their sides, rather than on their backs.