Wired has a good article on fires from “hoverboards,” which are essentially very small hands-free electric scooters. Here is an example. Start at about the :30 mark to see how these devices explode, and can easily set a house on fire.
Neither Wired nor other news stories have much constructive advice about how to reduce the chance of fires. As they point out, buying a well-made model is important, but at present there is no way to distinguish the well-made ones from the knock-offs. And most are cheap knock-offs by companies that will be gone in a year.
I have some experience with the underlying cause of these fires, their Lithium-based batteries, because I use them in radio controlled aircraft. Fires of these batteries are not common, but they happen. Two people in San Diego who I know directly have had major fires. One lost a 2-unit condo, the other a detached workshop. The second one happened to an expert in RC flying!