Helene has weakened to a tropical storm and is moving north across the Southeast, bringing strong winds and heavy rain in what the National Hurricane Center called "life-threatening" conditions.

COLUMBIA, S.C. — Two firefighters killed during Tropical Storm Helene in South Carolina were struck by a tree, authorities said. The tree hit their fire truck around 6:30 a.m. Friday about 4 miles (6 kilometers) west of Batesburg-Leesville, South Carolina Highway Patrol Cpl. David Jones said. Both firefighters died at the scene.

Helene made landfall in Florida's Big Bend late Thursday night and has triggered millions of power outages along the Atlantic coast.