The BBC reported that health and safety officials are now carrying out inquiries at the building in Ascot Drive to discover the cause of the accident.
The Wolseley-owned Build Center it was "shocked and saddened" by the incident.
The statement said: "We can confirm there was a fatal accident involving an employee at our Glass Center branch in Derby on Tuesday.
"We are extremely shocked and saddened by this tragic incident, and our thoughts and sincere sympathies are with the employee's family.
"We are cooperating fully with the relevant authorities with their investigations into this tragic incident."
"The safety of our employees is paramount to Build Center and we have had an excellent track record in this area. We are also conducting our own thorough investigation into what is believed to be the company's first workplace fatality."
Psychiatric Solutions selling business unit for $70 millionCivil engineering accidents at record low