A damaged Nikola battery-electric truck reignited at the company’s headquarters, one month after the truck was first affected by a fire.

In a statement, Nikola said that “no one was injured and the fire was quickly contained.”

The start-up said it suspected foul play was involved with the original fire, which is reported to have affected five trucks. It did not say how the damaged truck reignited.

The reignition has raised questions over the safety of Nikola’s battery packs. Romeo Power, a Nikola subsidiary, made the battery packs.

Nikola says the trucks were being closely monitored due damaged BEVs having a “higher-than-normal” likelihood to reignite.

Earlier this month the company announced it would liquidate Romeo Power, which it acquired less than a year ago for $144 million.