VICKSBURG, Miss. (AP) — LeTourneau Technologies Inc. has laid off 50 workers at its oil rig construction yard in Vicksburg.

Company spokesman Clay Masters says economic conditions prompted Friday’s layoffs. Masters did not offer any other details.

LeTourneau began as a munitions plant in 1944. Over time, it evolved into a global leader for building movable oil rigs. Rowan Companies Inc. of Houston, Texas, acquired the yard from Marathon Inc. in 1994 after a two-year shutdown, and it reopened in September 1995.