In a letter sent to employees last week, "heightened difficulty" experienced by the global economy and the rail industry was to blame for the closure. Safetran is a subsidiary of the United Kingdom-based Invensys Rail Systems.

In a letter to employees, Terri Wiethorn, vice president of human resources called the closure an "extremely difficult decision. The decision to close manufacturing operations at Rancho Cucamonga is a strategic business decision to ensure that the company's manufacturing operations are utilized in the most efficient way possible to remain competitive," according to the letter.

Safetran manufactures components for railroad signal systems and other communications devices.