The Consumer Product Safety Commission (CPSC) issued the strong warning to all Samsung Galaxy Note 7 users saying they should "power them down and stop charging or using the device."
The warning comes after some of the lithium-ion batteries in the Samsung Galaxy Note 7 phones caught fire during charging and normal use.
CPSC and Samsung are working cooperatively to formally announce an official recall of the devices, as soon as possible.
The FAA warned airline passengers with the Samsung Galaxy Note 7
to leave their phones off and not charging when flying.
The warning followed a voluntary global recall of the Note 7 that Samsung announced a week ago.
Last week, Samsung ordered a global recall of the Samsung Galaxy Note 7 phones after its investigation of explosion reports found the rechargeable batteries were at fault. In one case, a family in St. Petersburg, Florida, reported a Galaxy Note 7 phone left charging in their Jeep caught fire, destroying the vehicle.