Is there anything wrong with the Galaxy Note 7’s battery or its charging technologies? That’s a question Samsung is apparently trying to figure out after at least two devices exploded while charging. A new report from South Korea says the company suspended Galaxy Note 7 shipments to local carriers earlier this week, and the decision may be related to these reports of explosions.

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Citing Yonhap News Agency, The Korea Herald says that early this week Samsung suspended Galaxy Note 7 shipments to local telecom carriers, although the exact cause of the suspension has not been confirmed. It is believed that the explosions have something to do with it.

“Samsung has stopped supplying the phones even though preorders have not yet been shipped,” an unnamed official from a Korean wireless carrier said. “It is unclear whether the suspension is because of production constraints or a probe into the recent explosions.”

Sources told the Herald that Samsung collected the affected phones from customers and it’s investigating the matter. The company is expected to disclose its findings soon.

A few days ago, news broke out that a Galaxy Note 7 exploded while charging. That certainly sounds dangerous, but it’s not unheard of. Other mobile devices have suffered similar failures before, including iPhones. But a report from Business Korea says that a device exploded in Korea. That means at least two devices exploded while charging since the Galaxy Note 7 launched, which suggests that the first one wasn’t just an isolated incident.

The Herald notes that nobody was harmed in either of these incidents.

Meanwhile, it’s important to note that worldwide Galaxy Note 7 sales have not been halted. But until Samsung figures out if there’s a serious problem here, make sure you don’t leave your phone unattended while it’s charging — and make sure you use only the official Samsung equipment to charge it.