The Consumer Product Safety Commission is urging all consumers who own a Samsung Galaxy Note 7 to power them down, and stop charging or using the devices.
The warning comes amid recent reports involving the lithium-ion batteries in certain Note 7 devices resulting in fires.
The incidents have occurred while charging and during normal use, and prompted Samsung to halt sales of the phones last week and urge owners who have them to return it in exchange for another device.
In a written statement, the CPSC says it and Samsung are working together to formally announce an official recall of the devices, as soon as possible.
The CPSC says it's also working to determine whether a replacement Galaxy Note 7 is an acceptable remedy for Samsung or other phone carriers to provide to consumers.