A construction worker died yesterday after he was apparently struck by the boom of a concrete pumping truck at a condominium project site in Kaka'ako.

The accident happened about 11:06 a.m. at 1009 Kapi'olani Blvd., where the Moana Vista condominium project is under way. Bryan Cheplic, spokesman for the Honolulu Emergency Services Department, said the man was taken to the Straub Clinic & Hospital in critical condition.

He was pronounced dead at 12:07 p.m.

The man, 50, suffered severe head and other injuries.

James Hardway, of the state Department of Labor and Industrial Relations, said the man was struck when the sling of a tower crane got tangled up with the boom, causing it to shift. The sling was being used to transport materials from the seventh floor to the ground level.

When it got tangled up in the boom, the sling was empty and being lifted back up to the seventh floor, Hardway said. It's unclear whether the wind caused the sling to tangle up with the boom, or if it was negligence, Hardway said, adding that his office and police are investigating the death.

The victim was on the ground level when he was hit with the boom.

Work at the site stopped yesterday after the accident — the fifth construction site-related fatality in the Islands since Oct. 1, 2007, the start of the federal fiscal year, Hardway said.

The accident comes a week after a man was killed at an O'ahu work site when a piece of wood he was sanding on a machine hit him in the chest, Hardway said.