An autonomous food delivery robot burst into flames on a Berkeley, California walkway on Friday, as first reported by The Daily Californian. Kiwi, the startup that makes and manages the one hundred-strong fleet of robots, issued a statement to say that the fire was quickly extinguished by a passerby before the city’s fire department arrived and doused the machine in foam. No one was harmed as a result of the incident.

Kiwi suspended its service until it was able to complete its investigation. It said that it believed the fire was caused by human error, when a faulty battery was manually inserted into the robot, eventually causing thermal runaway — the same issue that resulted in the recall of Samsung’s Galaxy Note 7 phones. Kiwi says that a new piece of software will “rigorously monitor the state of each battery” to prevent anything like this from happening again.

Kiwi said the incident resulted in “some smoke and minor flames.” But video captured of the event shows the robot engulfed in the kind of fiercely burning fireball typically associated with battery fires.

The KiwiBots are currently only available in Berkeley, and are designed to handle the last 300 meters of food deliveries. Kiwi’s delivery process costs $3.80, and is formed of three different parts. First a robot carries a food order from a restaurant’s counter to the street, where it is then picked up by a courier on a tricycle. This courier then takes the food delivery to within a few hundred meters of its destination, before a KiwiBot is used to take it directly to a person’s door. The service launched in 2017, and as of May this year had made over 10,000 such deliveries with an average delivery time of 27 minutes, according to the company.

The incident comes at a critical time for the nascent robot delivery industry. Several companies including Starship, and more recently Postmates, have either announced or already begun testing their autonomous delivery services. However at least one city, San Francisco, has imposed limits on the use of these machines by requiring them to have permits and restricting their use to less-crowded areas of the city. Images of Kiwi’s flaming robot in a public space are unlikely to abate these concerns.