Delays with the production of the Tesla Model 3 has Elon Musk stressed out, and it just got worse: News from the Tesla plant on Monday is that work on the $35,000 electric has temporarily shut down.

Buzzfeed reported that workers at the Tesla plant in Fremont, California were sent home on Monday. Employees said there would be a pause in production of the Model 3 electric vehicle the next four to five days. Workers can use vacation days or go without pay, but some may be offered the option to work at another factory. The line was paused to “improve automation,” a Tesla spokesperson told the news outlet.

Elon Musk addressed the issues with the Model 3 in an interview with CBS This Morning on Friday. He said the mid-priced electric sedan had too much new technology and production should have been staged rather by workers rather than automated. He reiterated that point in a tweet saying, “Yes, excessive automation at Tesla was a mistake. To be precise, my mistake. Humans are underrated.”

This video shows Tesla Model 3 assembly.

At the beginning of April, Musk took control of the production of the Model 3. Since then he’s spent nights at the Tesla factory in order to attempt to solve issues and see the results of changes implemented. He’s also instituted more overtime hours for factory workers, which he said is paying off and putting the line back on track, although the recent news of the shutdown says otherwise.

When first announced, Tesla projected it would produce 5,000 Model 3s per week. On Friday, Musk said the production was now just more than 2,000 a week, but it was sustainable. Customers who pre-ordered the car last year would receive their vehicle in the next three to six months. How this pause in production will change the future of the Model 3 is yet to be determined.

“There’s vastly more automation with Model 3,” Musk told investment analysts in November during a conference call. “Now the tricky thing is that when one automation doesn’t work, it’s really harder to make up for it with men and labor. So with [Tesla Model] S or X, because a lot less that was automated, we could scale up labor hours and achieve a high level of production.”

The Model 3, by far the cheapest car Tesla has ever produced, is central to a company mission to boost production rates. Although the car has been “designed for manufacturing,” as Musk described it earlier this year, the Model 3 has 10,000 unique parts, meaning there’s tens of thousands of processes to produce each car. Any delays in this process can quickly build up.

(With background by Mike Brown.)

Photos via Tesla