On-site rescue headquarters have been set up as officials pumped out water on Thursday to reach the workers, whom rescuers have been unable to get to since the flood occurred around 3 a.m. Thursday, according to the Associated Press.

Local reports say the incident happened in the Shijingshan tunnel on the Xingye expressway in Zhuhai, Guangdong province. The expressway runs through the city of Zhuhai and connects to the Hong Kong-Zhuhai-Macao Bridge.

The city’s emergency management department said the operation is “proceeding in an intense and orderly way.”

Workers were about 0.7 miles from the tunnel’s entrance when a loud noise was heard and material started falling from the roof of the tunnel, according to Yan Dawu, the deputy general manager of the construction company.

An evacuation was ordered immediately, but water from the flood gushed into the tunnel and trapped 14 members of his team, Yan said at a news conference. The rescue team has been unable to get close to the tunnel’s opening because of the rapid flow of water flooding the tunnel.

“We feel deeply guilty and deeply blame ourselves,” he added.

The tunnel is located under a reservoir, which has made the rescue mission particularly tough. Although rescue teams have been able to plug the hole where the water was flooding in from, they are still trying to drain and pump the water out of both the tunnel and the reservoir.

The city’s emergency management department has dispatched eight emergency rescue teams from surrounding cities in Guangdong. As of Thursday morning, more than 1,000 rescuers, 22 fire trucks and five water-pumping vehicles have been mobilized for the effort.

The incident comes just months after two construction workers died in the same tunnel when a protective wall collapsed and they were hit by falling debris, according to a notice from the Zhuhai emergency management department.

Zhuhai is a coastal city near Macao and was one of China’s early special economic zones when the Communist Party started opening up the nation’s economy about 40 years ago.

Over the past week, southeast China has had heavy rains that have displaced thousands of people in the area.

The country saw the worst flooding in decades last year, and authorities have warned that the amount of rainfall this year could be even higher. In June, the Ministry of Water Resources issued a call for flood prevention efforts so communities can prepare for heavy rainfall that could last until August.