It wasn't clear whether Michael O'Brien died immediately from the impact or at a local hospital.
A worker toiling on the East Side Access tunnel under Grand Central Terminal was killed by falling concrete Thursday night.
Michael O'Brien was working on the tunnel, which aims to bring Long Island Rail Road service to Grand Central, when the heavy slab hit him about 8 p.m., according to the Metropolitan Transit Agency.
It wasn't clear whether O'Brien died immediately from the impact or at a local hospital. He was an employee of construction contractor Dragados.
O'Brien's father was working alongside his son when the concrete fell and attempted to revive him, according to the Daily News.
Work on the tunnel was suspended while authorities investigated the incident.