Local official Nguyen Xuan Truong says four workers died at the scene following the first accident Monday in the northern port city of Hai Phong. Two others died in a hospital, and four workers remain hospitalized.
The cause remains unclear, but falling rocks buried workers below and crushed them, he said.
Truong says a rock slide at a nearby quarry Tuesday killed three other workers.
The quarry operations produce limestone for cement factories and construction. (AP) Source