BANGKOK — With their elbows and knees scraping the walls as they wriggle through claustrophobic tunnels, rescuers are in a race against time to save two men still stuck in a cave in central Laos.

Seven men in search of gold were trapped in the mazelike cave network in Xaisomboun province more than a week ago when heavy rain and flash flooding blocked the only entrance. Five of them have since been freed as water levels dropped, including four who walked out on their own Saturday just as divers were getting ready to go in and get them.

On Monday, the focus narrowed on the remaining two men, as divers used ropes to rappel down into deep shafts, straining to hear clues for where they might be.

Kengkard Bongkawong, a Thai specialist cave diver whose Mettatham Association Rescue Unit is leading the high-stakes operation, said they were not giving up on their search, though he admitted he was feeling the pressure with lives on the line.

“The discouraged and tired feelings are a lot, I still feel I am failing in many things,” he told NBC News as he teared up while speaking from the site in an interview Monday.

“To be the operator and to be the leader, the pressure is so different,” said Bongkawong, who was also a key part of the team involved in the 2018 rescue of a dozen boys and their soccer coach from a cave in Thailand’s Chiang Rai province.

He said his team had been in and out of the Laos cave at least three times a day as the first five men were rescued.

“I think we did it, we made it and for the rest, we will try to do our best,” he said.

The high-tech rescue operation has unfolded as a multinational effort, with specialist divers also deployed from France, Australia, Finland, Malaysia, Japan and Indonesia. It relies on advanced terrain mapping technologies such as lidar, simultaneous cave drainage and carefully managed air supply for rescuers.

“Draining the water from the cave chambers is very important for the rescue team to work and also it helps adding the air layer in the chambers,” Bongkawong said.

“If they are still there, they have air to breathe,” he said of the two remaining men.

Laos has a rich mining sector, with several commercial copper and gold mining sites. It was gold that drew the men, all from a local village, into the cave despite warnings to the public from officials.

The Southeast Asian nation’s sprawling cave network is also a big tourist attraction, but Laos sees heavy rains this time of the year, making incursions particularly dangerous.

Another man who entered the cave with the others was able to escape before the exit was blocked and alerted the authorities.

When they were discovered Wednesday, the five men had ripped clothes and dirty faces, seemingly stunned that they had been found. The first survivor was brought out by divers Friday, giving the mission a burst of momentum a day before four others followed.

The two remaining men are believed to be deeper in the cave, though it’s unclear exactly where.

Divers have been pushing through tight crevices, with little light or air, and the constant risk that the weather could deteriorate and again flood the cave that rescuers have worked relentlessly to drain.

On Sunday, Bongkawong said, the divers descended more than 160 feet into the cave and used a hammer to knock the rock to signal to the last two men, hoping they would respond.

So far, there has been no positive confirmation. But he said rescuers are nonetheless focusing on draining the cave as fast as possible, hoping the last two men will be able to walk out by themselves.

“We set the system to drain the water, to build the pond, to build the road,” he said. “I will not let the nature control me, I will control the nature.”

Nat Sumon reported from Bangkok, Janis Mackey Frayer from Beijing and Mithil Aggarwal from Hong Kong.