NAHA, Okinawa Pref. (Kyodo) Four people who were carried away by a flash flood in Naha, Okinawa Prefecture, were found dead Thursday morning, police said.

Shigeyoshi Mori, 58, Tetsuo Adaniya and Masayoshi Nakamura, both 42, and Makoto Kiyuna, 39 were inspecting an old bridge Wednesday when the flash flood struck.

Mori was the field superintendent for the inspection, which was being carried out by Tokyo-based Mase Consultant Co. The other three were from a local construction firm.

Although Mase Consultant safety guidelines urge field workers to be aware of weather changes and have ropes on hand to rescue workers in the event of an emergency, workers can decide for themselves whether and when to suspend operations in the event of heavy rain.

Mase Consultant President Satoshi Mase has apologized for the deaths.

"I think there were inadequacies in our operational planning. We would like to apologize to the people who died and their families," Mase told a news conference in Naha.

Police have opened an investigation into whether proper steps were taken to ensure the safety of the four, they said.