The accident happened just after 10 a.m. in a building under construction at 9718 Fort Hamilton Parkway, said John Mulligan, a Fire Department spokesman.
One of the workers was taken to Victory Hospital, where he was pronounced dead on arrival. The other two were taken to Lutheran Hospital in serious condition, Mulligan said.
One of the injured men was identified as Baer Geum, 42. The names of the other two victims were not immediately released.