A worker at the construction site of the new San Francisco 49ers stadium died when a bundle of rebar he was unloading fell on him, the second workplace fatality at the stadium in recent months, according to state officials investigating the accident...[T]he worker was an employee of Gerdau Ameristeel, a subcontractor on Levi Stadium...In a statement, the 49ers said their "sincerest thoughts and prayers are with the family, friends and co-workers affected by this tragedy.''...An elevator mechanic...was killed at the construction site in June when he was struck by a counterweight while working in a shaft...[He] was employed by Schindler Elevator...a subcontractor for the stadium's general contractor, Turner-Devcon [part of Turner Construction].