Tesla Motors (TSLA) says that the fire that broke out in one of its Model S car on Tuesday was apparently sparked when a metal object struck a battery module under the vehicle.

The incident was captured on video and quickly went viral after being posted online. Model S cars, which are priced around $70,000, feature liquid-cooled, lithium-ion batteries located underneath the passenger compartment. No injuries were reported in the incident, which occurred outside Seattle. Firefighters extinguished the fire, which was confined to the front of the car, the Associated Press notes.

Water applied to the fire proved ineffective and authorities had to switch to a dry chemical extinguisher to put the fire out. The Model S owner reported that he felt something strike the car. He pulled over and got out before the fire started.

A Tesla spokesperson noted that the fire was “not a spontaneous event” but appeared to be the result of the impact of some sort of debris. The video’s appearance online caused Tesla shares to fall sharply in Wednesday trading.

Earlier this year, the worldwide fleet of Boeing‘s (BA) new 787 Dreamliner jets was grounded after a series of incidents traced to the planes’ lithium-ion batteries. 787s have since returned to the skies after the company developed a new containment system for the batteries.

Shares of Tesla dropped almost 3% in Thursday morning trading.