Debris lies on the ground at a Royal Dutch Shell Plc gas station damaged during Hurricane Florence in Wilmington, North Carolina, U.S., on Friday, Sept. 14, 2018.

Tropical storm Florence lumbered inland on Saturday, knocking down trees, flooding rivers, and dumping sheets of rain in the Carolinas where the death toll climbed to at least eight.

It diminished from hurricane force as it came ashore, but forecasters said the 350-mile-wide storm's slow progress across North and South Carolina could leave much of the region under water in the coming days.

By Saturday afternoon, Florence was inching west at 3 mph (6 kph), with its center located about 50 miles (85 kilometers) west of Myrtle Beach, South Carolina. Forecasters say prolonged rainfall from Florence could produce catastrophic flash flooding and significant river flooding.

Tropical storm-force winds stretched up to 150 miles (240 kph) from the storm's center.

"This storm is relentless and excruciating," North Carolina Governor Roy Cooper told CNN late on Friday. "There is probably not a county or a person that will not be affected in some way by this very massive and violent storm."

A mother and baby were killed when a tree fell on their home in Wilmington, North Carolina. The child's injured father was taken to hospital. In Pender County, a woman died of a heart attack; paramedics trying to reach her were blocked by debris.

Two people died in Lenoir County. A 78-year-old man was electrocuted attempting to connect extension cords while another man died when he was blown down by high winds while checking on his hunting dogs, a county spokesman said.