Tesla shares fell Friday after news of another California state government probe into a workplace injury days after the same agency said it would look into workplace safety at Tesla's facilities.
California's Occupational Safety and Health Administration, or Cal-OSHA, confirmed the investigation.
"Cal/OSHA on Thursday, April 12 opened a multi-employer accident investigation with the Kansas City, Missouri-based subcontractor and with Tesla," said a statement from the agency. "Cal/OSHA is investigating the cause of the incident and has six months to issue citations for any violations of workplace safety regulations."
The news was first reported by Bloomberg.
A worker employed by subcontractor Automatic Systems reportedly broke his jaw when he was hit by a skid carrier at Tesla's assembly plant in Fremont, California.
Tesla shares were down 2.7 percent midafternoon Friday.
"Nothing is more important to us than the safety and well-being of those who work at Tesla every day," Tesla said in a statement sent to CNBC. "This injury involved a worker who had been hired by an independent contractor and was performing a procedure that had been developed by and was under the supervision of that contractor. This contractor was also responsible for reporting the injury, which they did. We take any injury very seriously, and we'll of course provide our full cooperation to Cal-OSHA."
The news comes days after Cal-OSHA said it was opening an investigation into workplace safety, after a report from RevealNews.org that said Tesla has mislabeled and undercounted injuries to make its safety record appear better than it is.
The electric-car maker disputed that report with a blog post Monday.
Tesla is scrambling to ramp up production of the Model 3, a car Tesla is marketing as a more affordable alternative to its high-end electric vehicles. The company has repeatedly missed its own production targets. An email leaked earlier this week detailed CEO Elon Musk's plan to speed up production.