Police launched an investigation into the deadly accident at a building under construction in the Gyeonggi provincial city of Anseong on Wednesday.

The Gyeonggi Nambu Provincial Police Agency said on Thursday that it began questioning injured workers and other witnesses, while obtaining surveillance footage from the site where the top floor of the nine-story building collapsed onto the floor below.

The police, fire authorities and forensic experts plan to conduct a joint inspection of the construction site at an unspecified date, while investigators are expected to charge those found responsible with gross occupational negligence causing death and injury.

The labor ministry is also looking to apply the Serious Disaster Punishment Act against the builder involved in the project.

The incident resulted in the deaths of two Vietnamese workers who were brothers and injuries to four others.