The seven entered the cave in Laos’ central Xaisomboun province on May 20 but got trapped by a landslide triggered by heavy rain, according to a local rescue group and the state-run Lao Phattana News.

A Thai rescue team joined the operation on Sunday and reported significant progress towards reaching the chamber where the group was trapped.

“From this moment on, I believe our success is not far away,” Kengkard Bongkawong, head of the team, said in a social media post on Monday.

The team is working alongside a local group, the Laos Rescue Volunteer for People, which said the seven people had entered the cave looking for gold. The country’s disaster agency could not be reached for comment.

Footage posted on the Facebook page of Lao Phattana News showed rescuers in helmets crawling through tight spaces under torchlight, gasping for breath, and others wading slowly through muddy, chest-high waters deep into the cave.

The team includes a diver involved in a 17-day rescue at a flooded mountain cave in Thailand in 2018 that captured global attention, when specialists from around the world, including US military personnel and Thai Navy SEALs, descended on the province of Chiang Rai to free a junior soccer team named “Wild Boars”.

Kengkard, who heads a volunteer disaster and rescue team in northeastern Thailand, said water pumping would continue day and night, after the team broke through sand and gravel to edge closer to an underwater shaft they believe will lead them to those trapped.

He said a survey of the area above the cave found four shafts that could potentially connect to the cave system and provide an additional route for the rescue.

“We estimate that less than 20 metres remain before we reach the key target area,” he said.