A Samsung smartphone exploded while charging on a Winthrop paramedic’s bedside table early Saturday, one day after the company recalled millions of Galaxy Note 7 models amid reports that they are at risk of spontaneously combusting.

The Winthrop explosion occurred inside the sleeping barracks at Action Ambulance Service Inc. just before 6:30 a.m., said Captain Scott Wiley of the Winthrop Fire Department.

No one was injured, Wylie said, though smoke from the explosion was enough to trigger the building’s fire alarm.

“The battery was melted out through the back and the screen was melted in,’’ said paramedic Shane McKenney, who arrived for his morning shift shortly after the phone of his coworker, paramedic Steve Enright, exploded.

“His phone blew up while it was right next to him,’’ McKenney said. “He was freaked out.’’

The ambulance service said via Facebook that the phone was a Galaxy Note 7.

On Friday, Samsung said in a statement it would stop selling the popular phones in international markets because faulty batteries could cause fires or explosions.

The company has pledged to replace the smartphones and credit consumers $25 “over the coming weeks.’’

A Samsung spokesman said in an e-mail Sunday that the company is aware of the Winthrop incident and makes consumer safety its “highest priority.’’

Jennifer Meith, spokeswoman for the state Department of Fire Services, said owners of the recalled model should stop using it altogether.

“You should make arrangements to get it replaced right away,’’ said Meith said.

She said all smartphone owners should take precautions while charging their devices, including not overcharging, using an off-brand charging cord, or failing to charge on a well-ventilated surface.

Amanda Burke can be reached at amanda.burke@globe.com. Follow her on Twitter @charlie_acb.