The 14 construction workers who were trapped when the tunnel they were working on in southern China suddenly flooded early Thursday morning still cannot be reached, officials said at a press conference Friday afternoon.

The tunnel, located in Guangdong province’s Zhuhai, is part of the Xingye Highway that will connect with the Hong Kong-Zhuhai-Macao Bridge.

Water suddenly rushed into the tunnel at around 3:30 a.m. on Thursday. The group of workers were about 1.1 kilometers from the tunnel entrance, and could not evacuate in time, officials said. The workers have not been in contact with the outside world since.

A rescue team of over 1,000 people are trying to reach the trapped workers, but their efforts have been hampered by the strong flow of water entering the tunnel. Aided by pump vehicles on site, the water level in the tunnel is dropping. By Friday noon, the rescue team had advanced to a point about 750 meters away from the trapped workers.

The tunnel passes through the Jida reservoir, which on Thursday was ordered to release water. The local agriculture and water authority warned residents to stay away from a nearby river and drainage channels.

According to a local media report from 2019, the tunnel’s trajectory through the water reservoir required cutting-edge construction methods and technologies, including high-standard anti-water leakage measures. Experts reportedly called the project “a museum of tunnel construction.”

In March, two workers died when another section of the tunnel collapsed, according to a document from the local emergency management department.

It is the second construction-related accident in China this week. On Monday, a hotel where renovation work was reportedly ongoing collapsed in Suzhou, eastern China, killing 17 people.

Contributions: Zeng Chuchu; Kevin Schoenmakers.

(Header image: An aerial view of the tunnel construction site in Zhuhai, Guangdong province, July 15, 2021. Yi Heng/People Visual)