Rescue workers were trying to reach three people trapped inside a high-speed railway tunnel that collapsed in Nakhon Ratchasima's Pak Chong district during construction on Saturday night.
The tunnel collapsed in tambon Chan Thuek at 11.30pm on Saturday while two workers were operating a backhoe and a truck to dig the tunnel. A foreman who had just arrived in a car was the third person trapped in the tunnel. There was no rain at the time of the collapse.
Later, officials said two of the three missing were Chinese. The other missing person was a Myanmar truck driver.
The section of the tunnel that collapsed was about four kilometres from its entrance.
An initial investigation found that the section that collapsed might be 10-30 metres long in an area where the tunnel walls were being built.
The government is building a 251 kilometre-long section of the Sino-Thai high-speed rail link between Bangkok and Nakhon Ratchasima. The section is expected to be completed in 2028.
The Muak Lek-Lam Takhong tunnel was designed to be about eight kilometres. It was 74% completed.
