Clarification: An earlier version of this article suggested that the NTSB investigation had just begun. The article has been updated to clarify that the NTSB reported preliminary results of the investigation Tuesday.

The National Transportation Safety Board on Tuesday issued preliminary findings from an investigation into a Tesla Inc. TSLA, -7.94% Model S battery fire on June 15 in Santa Monica, Calif. According to the NTSB, a Model S was traveling on June 15 on Santa Monica Boulevard when other drivers flagged smoke coming from the underside of car. The driver, a 44-year-old man, was able to get out, and there were no injuries. A bystander's video showed flames shortly after. Firefighters responded and the flames were "quickly extinguished," and the Model S was towed, the NTSB said. Tesla has conducted an initial inspection and the car was relocated for further inspection. "The NTSB initiated an investigation into this incident to obtain information about electric-powered vehicle fires," it said in a statement. It will use information from this and other investigations, including a fatal crash and fire in Mountain View, Calif., "to address safety issues encountered by first responders and others during crash scene stabilization and vehicle recovery operations involving electric-powered vehicles," it said. "All aspects of the incident remain under investigation," it said. Tesla shares fell 4% on Tuesday, looking poised to end at their sixth straight loss, and traded as low as $292.60. Tesla could not immediately be reached for comment. The NTSB in June released a preliminary report about the Mountain View crash, saying that the Model X involved had sped up in the final seconds before the accident and Autopilot, Tesla's suite of advanced driver-assistance features, was on.