Government safety officials are urging anyone with the recalled Samsung Galaxy Note7 to stop using the device immediately.
The Consumer Product Safety Commission issued the strong warning to all Note7 users Friday, 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 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 on Thursday warned airline passengers with the Samsung Galaxy Note 7 to leave their phones off and not charging when flying.
Last week, Samsung ordered a global recall of the jumbo 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 Note7 phone left charging in their Jeep caught fire, destroying the vehicle.
Any problems with the Samsung phones or other consumer products can be reported to the CPSC at www.SaferProducts.gov.
Samsung said it has been working with the commission on corrective actions, including a U.S. recall of the product.
"Samsung continues to ensure that consumer safety remains our top priority. We are asking users to power down their Galaxy Note7s and exchange them now," said Tim Baxter, president of Samsung Electronics America. "New Note7 replacement devices will be issued to exchange program participants upon completion of the CPSC process. In the interim, consumers can return their Note7 for another device."
The company has established an exchange program for the Note 7. Details of the program are available online here or by calling the company at 1-800-SAMSUNG.
Samsung Galaxy Note 7 users should stop using phone, federal agency warns