Diamond Shamrock will lay off 600 employees.

The company cited a “streamlining of the corporation” brought on by declining oil prices for the layoffs, which represent about 5% of its 11,500 workers. “The streamlining will be complete by May 1, and all affected employees should know their status no later than that date,” the company said in a statement. Diamond Shamrock said it has not decided which workers will be laid off. The company said the board of directors decided to “focus the corporation’s resources on the oil and gas business,” and will consider selling Diamond Shamrock Chemicals in Irving, Tex., and Diamond Shamrock Coal in Lexington, Ky.