The U.S. Consumer Product Safety Commission and Samsung are urging owners of the Galaxy Note 7 smartphones to stop using the devices while they work to formalize how a recall will work.

The warning comes a week after Samsung (SSNLF) announced a voluntary recall of 2.5 million phones worldwide because of a battery problem believed to affect 0.1% of all devices. Some customers reported that their Note 7s caught fire.

A government recall would outlaw the selling of the phone. In its statement, the agency asked owners of the Note 7 "to power them down and stop charging or using the device" in the meantime.

Details on an official recall will come "as soon as possible," the agency said.

Tim Baxter, president of Samsung Electronics America, said the company is collaborating with CPSC and its carrier partners to ensure all Note 7 users are alerted.

Read more at CNN.