Rescue inside tunnel Photo: Screenshot of a video posted by The Beijing News

All 14 construction workers trapped in a waterlogged tunnel in Zhuhai, South China's Guangdong Province, were found dead on Thursday. The government will fully assist with the following investigation, said the Zhuhai government.

---Wednesday---

Another 10 among 14 trapped workers were found dead on Wednesday. The death toll rises to 13 as of 11:00 pm Wednesday. One worker remains missing, according to a statement Zhuhai government posted. 

The rescue team are getting closer to the trapped workers, said the statement. 

---Tuesday---

Three workers have been found dead as of 8 am on Tuesday, said local government officials. This comes five days after the incident occurred.

The rescue team has moved forward 856.1 meters into the tunnel, with 303.9 meters left to reach the trapped people. The overall water level in the tunnel has dropped by 16.5 meters, said Huang Zhihao, mayor of Zhuhai and chief of the onsite rescue command, at a press conference on Tuesday. 

More than 2,500 rescuers of 46 teams from Zhuhai and other provinces have been dispatched for the search and rescue work in the past five days, Huang said. At the rescue site, there are still nearly 2,000 people and more than 400 sets of equipment working around the clock, said another official. 

Sun Zhang, professor at the Institute of Rail Transit of Tongji University, told the Global Times on Tuesday that in tunnel construction, geological detection is usually conducted in advance before excavation to find possible adverse geological conditions. But unexpected incidents might still occur in complex terrain. 

One worker who escaped from the incident was quoted as saying in a report by Jimu News on Tuesday that as soon as the water poured in, the tunnel was rapidly filled to the top and many people were swept away. He was fortunate to be able to grab a wire and climbed to a platform five or six meters high, along with three other villagers, but after only a minute or two, the water was up to his waist again. 

The four of them later swam toward the opening of the tunnel, but two behind him disappeared after going for nearly one hundred meters. After swimming another six or seven hundred meters, he found that he was able to stand up in the water. He, along with another worker, finally made it to the end.

---Monday---

Two victims were found about 1,060 meters and 1,070 meters from the tunnel's left hole entrance at 3:20 pm and 3:38 pm on Monday, according to a statement from the rescue command onsite released Monday.

--- Sunday --- 

The rescue team has advanced 598.5 meters into the tunnel, but still 561.5 meters away from the trapped people, said a Zhuhai government official on Sunday. 

The overall water level in the tunnel has dropped by 11.3 meters. Professional diving teams have been sent, but no trapped workers have been found yet, said Zhang Yisheng, vice mayor of Zhuhai, at a press conference on Sunday. 

To push forward the rescue process as fast as possible, Zhang said the rescue team has been draining the water from the tunnel while filling and sealing the leakage points on the tunnel roof. 

10 sets of 14 drainage equipment have been relayed to pump out the water from the tunnel. Meanwhile 686.9 cubic meters of grouting volume have been completed accumulatively as of 9 am Sunday. The sealing of the points that were leaking has already finished. 

Efforts have also been made in pumping up the reservoir, from where the reportedly initially poured into the collapsed tunnel. More than 253,000 cubic meters of water have been drained off by 51 machines, said Lu Xiaobo, head of Zhuhai Water Administration, at the press conference.

Though the decrease in the water level of the reservoir has strongly supported the rescue work, challenges still remain in pushing it forward, said Lu. 

The operation of the drainage equipment is restricted by a complicated terrain inside the reservoir, and the sudden drop of water level in the reservoir also affects the safe operation of the dam, he said, noting that the continuous rainfall expected to come in the next few days in Zhuhai will not be helpful with the drainage process of the reservoir.

Since the incident occurred at 3:30 am on Thursday, 14 construction workers have been trapped in the tunnel, which is 1,160 meters away from its opening, for more than 80 hours. 

The rescue team has advanced 598.5 meters into the tunnel as of Sunday morning, moving forward at an average rate of around 100 meters in the past two days. However, they have advanced only half way, with 561.5 meters left to go to reach the trapped people. 

Seven professional diving teams have been employed for search and rescue. 25 frogmen, two underwater robots and seven unmanned ships have been dispatched, and the total underwater search time has exceeded 20 hours. 

While engaging in the rescue work, experts onsite are also closely monitoring the concentration of carbon monoxide in the tunnel and strengthening ventilation to prevent the occurrence of secondary disasters, Zhang said.  

This is a developing story.