Nikola Corp said Friday it suspected “foul play” in a fire outside of its Phoenix headquarters that affected some of its battery electric trucks.

The fire, which Nikola tweeted about and has since confirmed with TechCrunch, started early this morning behind its headquarters. A vehicle was seen in the area of the affected trucks just prior to the incident and an investigation is underway.

“Our team applauds the Phoenix and Tempe Fire Departments for taking quick action and staying on top of the situation,” the company tweeted. “We will release additional information as it becomes available.”

The company didn’t provide details about exactly how many vehicles were affected, only noting that it involved “multiple” trucks.

Shares were down about 8% to $1.27.

The fire occurred a week after the beleaguered EV truck company announced it was laying off 270 employees, or about 23% of its workforce, and restricting its electric truck efforts to North America as it seeks to preserve cash. About 150 workers who were supporting the company’s European programs were cut. Another 120 employees based at the company’s Phoenix and Coolidge, Arizona, sites also lost their jobs. About 900 employees remain.

Nikola said the cuts are expected to decrease personnel-related cash spend by more than $50 million annually. As a result of the cuts, the company’s annual cash spend is expected to decrease to under $400 million by 2024.