Hoverboards were a hot holiday gift idea. Now, they’re exploding.

Overstock.com became the first major retailer on Thursday to ban sales of hoverboards over “safety concerns” as reports continue to pile up that the self-balancing electronic scooters are spontaneously bursting into flames.

Videos of exploding hoverboards have spread like wildfire across the Internet, most recently one of a flaming hoverboard being doused by fire extinguishers on Wednesday at a mall in Washington state.

The Consumer Product Safety Commission has launched 10 active fire-related hoverboard probes across nine states, said spokesman Scott Wolfson.

“That number increased from yesterday to today, and it could continue to increase,” Wolfson said on Thursday.

That’s in addition to more than 30 reports of hospitalizations on hoverboard-related injuries — many of them serious, including head wounds and major trauma to arms and legs.

The fires appear to be sparked by the hoverboard’s lithium-ion batteries, which had caused similar problems a decade ago with mobile phones and laptop computers.

In those cases, the CPSC developed safety standards that curbed the problem. Experts say hoverboards, which are mostly manufactured by small companies in China under unregulated conditions, are in dire need of such standards now.

Nearer-term, some hoverboards could face recalls as the CPSC inspects problem models at a facility in suburban Washington, D.C., and fields incidents reported to its saferproducts.gov site. The CPSC also could block imports of risky devices.