Two workers were killed and two others were injured Monday after they fell more than 20 meters when steel scaffolding for a ship under construction collapsed in Kure, Hiroshima Prefecture, police and the vessel's builder said.

The four were helping construct a 90,000-ton containership for a German client at a shipbuilding dock of IHI Marine United Inc.

The accident took place shortly after 9 a.m. when the scaffolding suddenly collapsed and the four working on it fell along with a 246-ton steel section that came loose from the ship.

The dead workers were identified as 26-year-old Naruto Yamazaki, an employee of a Kure company taking part in the construction of the ship, and Takahisa Kobayashi, an employee of an IHIMU subsidiary.

IHIMU employee Mitsuhiro Otoshi, 59, suffered severe injuries, and Masahiko Hashimoto, 22, an employee of the Kure company, received a minor injury.

Police said they opened an investigation into the accident.

It was windy in Kure early Monday morning, but it is unknown if the weather had anything to do with the incident.