Luxury electric vehicle maker Tesla fired about 400 employees this week, including associates, team leaders and supervisors, according to a former employee. The dismissals were a result of a company-wide annual review, Tesla said in an emailed statement, without confirming the number of employees leaving the company.

"It's about 400 people ranging from associates to team leaders to supervisors. We don't know how high up it went," said the former employee, who worked on the assembly line and did not want to be identified. Though Tesla cited performance as the reason for the firings, the source said that he was fired in spite of never having been given a bad review.

The California-based company said earlier in the month that "production bottlenecks" had left Tesla behind its planned ramp-up for the new Model 3 mass-market sedan. The company delivered 220 Model 3 sedans and produced 260 during the third quarter.