The National Safety Transportation Board announced on Tuesday that it is investigating a fatal car accident involving a Tesla vehicle that occurred in Mountain View, California, last Friday. Tesla stock lost 8 percent in trading yesterday, and it was down an additional 4 percent in early trading on Wednesday.

“Unclear if automated control system was active at time of crash,” the NTSB wrote. “Issues examined include: post-crash fire, steps to make vehicle safe for removal from scene.”

Here is the scene on Highway 101S in #MountainView where a #Tesla caught on fire pic.twitter.com/ksnidlFgsw

— Dean C. Smith (@DeanCSmith) March 23, 2018

Tesla provided some context about the crash in a Tuesday blog post after the NTSB made its announcement. “The reason this crash was so severe is that the crash attenuator, a highway safety barrier which is designed to reduce the impact into a concrete lane divider, had either been removed or crushed in a prior accident without being replaced,” Tesla wrote.