A Vietnamese crane operator has been sentenced to five years in jail for his fatal irresponsibility at work that resulted in the deaths of a mother and her two children, a local court ruled on Wednesday.

The convicted 30-year-old construction worker, Nguyen Thai Quynh, stood trial on February 24 at the People’s Court of Hong Ngu District in the Mekong Delta province of Dong Thap.

Quynh was charged with “accidentally causing human death due to breach of professional regulations.”

The accident occurred on May 5, 2015 at the construction site of the Hong Ngu 2 Bridge, supervised by Truong Loc Constructions JSC.

According to the indictment prepared by the People’s Procuracy of Dong Thap, Quynh was in charge of operating the crane to move a cement tank at the time of the incident.

He had asked three workers to help re-direct traffic moving in the range of the crane, but was found to have started the work before the others could get into position.

The crane bent under the weight of the overloaded cement tank before finally giving way and collapsing onto the moving traffic below.

A 32-year-old mother, Cao Tuong Van, and her two children, six-year-old Tran Cao Cong Danh and three-year-old Tran Ngoc Thao Vy, were killed instantly.

Quynh gave vague answers in court when asked repeatedly by the judges whether he knew the maximum capacity of the crane and the weight of the cement tank at the time.

“Cranes in general can lift things weighing up to six, seven or eight metric tons,” Quynh said. “About the tank, I heard it weighed four metric tons or so, plus some hundred kilograms of cement inside.”

Inspection results proved otherwise, showing the crane could lift up to seven metric tons while the cement tank weighed 10.6 metric tons in total, exceeding its maximum capacity by 1.5 times.

In addition, Quynh confessed that the construction manager was not present at the site and had not given prior instructions on moving the tank.

The sentence for Quynh was five years in prison, while Truong Loc Constructions JSC is now required to pay VND8 million (US$350) in indemnification to the victims’ family.