* Mother and infant killed by falling tree
* N. Carolina governor: Storm in ‘violent grind’ across state
* More than 720,000 customers without power in Carolinas (Recasts lead; adds comment)
By Ernest Scheyder
WILMINGTON, N.C., Sept 14 (Reuters) - Florence plowed into the Carolinas and lumbered slowly inland on Friday, knocking down trees, gorging rivers, dumping sheets of rain and leaving five people dead before it was downgraded to a tropical storm still capable of wreaking havoc.
Though Florence’s shrieking winds diminished from hurricane force as it came ashore, forecasters said the sheer size of the 350-mile-wide storm and its painfully slow progress across North and South Carolina in the coming days could leave much of the region under water.
The dead included a mother and baby who were killed when a tree fell on their home in Wilmington, North Carolina. The child’s injured father was taken to a hospital. In the state’s 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 perished when he was blown down by high winds while checking on his hunting dogs, a county spokesman said.
In New Bern, North Carolina, the storm surge overwhelmed the town of 30,000, located at the confluence of the Neuse and Trent rivers.
Jay Manning said he and his wife watched with alarm as water filled the street.
“We moved all the furniture up in case the water comes in but the water seems to be staying at the edge of the driveway,” he said, adding that if the wind picks up and the rain keeps coming, that could change. “My wife’s in a panic right now.”
Florence had been a Category 3 hurricane on the five-step Saffir-Simpson scale with 120-mph winds as of Thursday, but dropped to a Category 1 hurricane before coming ashore near Wrightsville Beach close to Wilmington.
The National Hurricane Center downgraded it to a tropical storm on Friday afternoon, but warned it would dump as much as 30 to 40 inches of rain on the southeastern coast of North Carolina and into the northeastern coast of South Carolina in spots.
“This rainfall will produce catastrophic flash flooding and prolonged significant river flooding,” the hurricane center said.
Atlantic Beach on North Carolina’s Outer Banks islands had already received 30 inches (76 cm) of rain, the U.S. Geological Survey said.
By Friday night the center of the storm had moved to eastern South Carolina, about 15 miles northeast of Myrtle Beach, with maximum sustained winds of 70 mph.
North Carolina utilities have estimated that as many as 2.5 million state residents could be left without power, the state’s Department of Public Safety said. More than 22,600 people were housed in 150 shelters statewide, including schools, churches and Wake Forest University’s basketball arena.
Officials in New Bern, which dates to the early 18th century, said over 100 people were rescued from floods and the downtown was under water by Friday afternoon. Calls for help multiplied as the wind picked up and the tide rolled in.
“These are folks who decided to stay and ride out the storm for whatever reason, despite having a mandatory evacuation,” city public information officer Colleen Roberts said. “These are folks who are maybe in one-story buildings and they’re seeing the floodwaters rise.”
New Bern resident Dan Eudy said he and his brother were awakened on Thursday night by the sound of a boat ramming against his front porch. They ventured out in life jackets into waste-deep water to tie the boat and another floating by to a tree.
Eudy and his family stayed home in New Bern partly to protect their house. “And we had no belief it would be as significant an event as it was,” he said. “This is a 500- or 1,000-year event.”
The White House said on Friday that President Donald Trump had spoken with state and local officials, assuring them the federal government was prepared to help. Trump planned a visit to the region next week.
The storm was expected to move across parts of southeastern North Carolina and eastern South Carolina on Friday and Saturday, then head north over the western Carolinas and central Appalachian Mountains early next week, the NHC said. Significant weakening was expected over the weekend.
About 10 million people could be affected by the storm.
Florence was one of two major storms threatening millions of people on opposite sides of the world. Super Typhoon Mangkhut was expected to hit an area in the Philippines on Saturday that would affect 5.2 million people.
Additional reporting by Gene Cherry in Raleigh; Scott DiSavino and Gina Cherelus in New York; Makini Brice in Washington; Andy Sullivan in Columbia, South Carolina; and Brendan O'Brien in Milwaukee; writing by Bill Trott and Dan Whitcomb; Editing by Bill Tarrant and Leslie Adler