At least 12 workers have been killed by collapsing scaffolding during a seawall-building project in Vietnam's Ha Tinh province.
More than 20 other people working on the site in the Vung Ang economic zone were injured in the incident late on Wednesday, said officials.
A spokesman for the zone, Pham Tran De, said rescue workers were searching the rubble in case people were trapped.
The workers were subcontractors for a branch of South Korea's Samsung group.
Mr De told the VnExpress news website there were thousands of people on site at the time "so the number of workers in distress is not yet accurately calculated".
"Authorities are actively removing the rubble to rescue the trapped workers," he said.
The Vung Ang zone was the scene of violent anti-Chinese protests last year following territorial disputes between China and Vietnam over the South China Sea.
