Three workers died after falling during crane dismantling work at a steel plant in Kawasaki, Kanagawa Prefecture, police said, as authorities resumed a search Wednesday for another worker who remains missing.

The accident occurred around 4:15 p.m. Tuesday at the Keihin district of JFE Steel*s East Japan Works. Five male workers fell when scaffolding collapsed during the dismantling of a large crane used to move iron ore from ships, according to investigators.

Police said a counterweight on the crane fell for unknown reasons, triggering the collapse of the work platform.

Four workers, including the three who later died, were taken to a hospital. The fourth worker is believed to be seriously injured, according to the Yomiuri Shimbun. The fifth worker remains unaccounted for and may have fallen into the sea, authorities said.

The deceased have been identified as Katsuki Ueyama, 43, Kenshiro Chiba, 19, and Yu Koike, 29?〞 all from Chiba Prefecture.

According to the Asahi Shimbun, the prefectural police, along with the fire department and the Japan Coast Guard, conducted a dive search on Tuesday, but it proved difficult due to debris and other obstacles. The search was suspended during the night.

On Wednesday, the search was being conducted by boat, as well as other methods.

Kanagawa Prefectural Police are working to confirm the identities of the remaining victims and are investigating the cause of the accident, including whether professional negligence resulting in death or injury might have occurred.

Information from Jiji added