Blue-collar workers have been back in the factory for a little over a week now and now GM's white-collar workers are starting to slowly repopulate its office in Warren, Michigan.

"A small number of employees have returned to work at the Tech Center campus, following the safety guidelines we have communicated," Jim Cain, a GM spokesman, told the Detroit Free Press this week. "We will have employees returning to other sites in phases based on a number of factors, with health and safety the No. 1 consideration."

When and how employees will return to work at GM's headquarters in Detroit, its Technical Center and Proving Grounds in Milford, is not yet known. Cain said GM is not ready to discuss the details publicly.

Those offices have roughly 25,000 employees between them, though. The Detroit Free Press spoke to two unnamed sources, who relayed that the plan to return those white-collar workers will happen in four steps.

The first started on May 18, with people who could not work remotely returning for limited amounts of hours each week. The second phase does not yet have a date but will include employees who can work remotely but are more effective in the office.

The third step will bring back workers who can do their works remotely, and the final step will be a return to normal operations. The dates for steps two through four have not yet been finalized and will likely depend on external factors.