SEATTLE (AP) — Federal and state officials say they have begun investigating the partial collapse of a pier along Seattle's waterfront as workers were demolishing portions of it.

The inspectors will investigate the city and two contractors involved in the demolition project before a 15,000-square-foot (1,394-square-meter) piece of the pier broke into the water, the Washington State Department of Labor and Industries said Monday. The contractors being investigated are Orion Marine Contractors and Evergreen Concrete Cutting, the Seattle Times reported.

Five workers were on the pier when part of it began to collapse, according to the city's Office of the Waterfront. Workers were quickly evacuated, but not before two men fell into the water. Both were promptly rescued by safety staff.

Measures to demolish Pier 58, home of Seattle's Waterfront Park, were accelerated after a gap was discovered between the pier and the adjacent land. The pier was originally scheduled to be replaced in 2022.

The Seattle Aquarium, located adjacent to the pier, was not affected by the collapse, officials said.

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