Three foreign workers trapped inside a collapsed train tunnel have died despite rescue efforts that lasted over five days, Thai authorities have confirmed.
The men, two from China and one from Myanmar, were believed to be alive as recently as Thursday.
They became trapped when part of the tunnel they were constructing collapsed on Saturday in Pak Chong district, approximately 200 km (124 mi) northeast of Bangkok.
On Friday, authorities announced that all three had died, with initial investigations suggesting a lack of air as the cause.
The tunnel, part of the Thailand-China high-speed railway project, collapsed due to a landslide at around 23:40 local time (16:40 GMT) last Saturday.
Rescuers, including officials from the State Railway of Thailand (SRT) and a Chinese disaster response team, had been working around the clock over the past week in hopes of saving the trapped workers.
Efforts were made to pump oxygen into the tunnel to keep the workers alive, but it remains unclear whether the tubes reached them.
On Thursday, rescuers discovered the body of a Burmese truck driver buried under a pile of soil and rocks.
The bodies of the two Chinese workers, a supervisor and an excavator operator, were found around 06:00 local time (00:00 GMT) on Friday, according to the SRT.
All three bodies were located approximately 25 meters from the point where the tunnel collapsed, officials reported.
Local sources indicated that rescuers had come within just one meter of one of the men on Wednesday. That same day, faint sounds believed to be from the workers were reportedly heard.
Scanners and sniffer dogs also detected vital signs, raising hopes that the workers might still be alive.
However, rescue efforts were hindered by the ongoing landslide, as falling dirt continually blocked the holes made by rescuers as they attempted to penetrate deeper into the tunnel.
Thailand’s caretaker Interior Minister Anutin Charnvirakul said rescuers were hindered by “the limitation of engineering”.
They had to be careful that their digging would not cause other parts of the tunnel to collapse, he said, adding that the rescuers had to build 3m (9.8ft) high supporting structures for their own safety.
“Nobody wanted [this incident] to happen,” he said at a press conference on Friday.
“We did not only try to save the lives of the victims, we also had to [ensure the safety] of the rescuers and workers,” he said.
The bodies of the three men were recovered from the tunnel on Friday.
Thai police have launched an investigation into the incident, and construction work around the tunnel has been temporarily suspended.