* Death toll rises to at least 877 in Haiti
* Storm gradually weakening off U.S. coast - NHC
* Mass evacuations in four U.S. states
Hurricane Matthew killed almost 900 people and displaced tens of thousands in Haiti before plowing northward on Saturday just off the southeast U.S. coast, where it caused major flooding and widespread power outages.
The number of deaths in Haiti, the poorest country in the Americas, jumped to at least 877 on Friday as information trickled in from remote areas previously cut off by the storm, according to a Reuters tally of tolls from officials.
Matthew rampaged through Haiti's western peninsula on Tuesday with 145 mph (233 kph) winds and torrential rain. Some 61,500 people were in shelters, officials said, after the storm hurled the sea into fragile coastal villages, some of which were only now being contacted.
At least three towns in the hills and coast of Haiti's fertile western tip reported dozens of people killed, including the farming village of Chantal where the mayor said 86 people died, mostly when trees crushed houses. He said 20 others were missing.
"A tree fell on the house and flattened it. The entire house fell on us. I couldn't get out," said 27-year-old driver Jean-Pierre Jean-Donald.
"People came to lift the rubble, and then we saw my wife who had died in the same spot," said Jean-Donald, who had been married for only a year. His young daughter stood by his side, crying "Mommy."
With cellphone networks down and roads flooded, aid has been slow to reach hard-hit areas in Haiti. Food was scarce and at least seven people died of cholera, likely because of flood water mixing with sewage.
The Mesa Verde, a U.S. Navy amphibious transport dock ship, was en route to Haiti to support relief efforts. The ship has heavy-lift helicopters, bulldozers, fresh-water delivery vehicles and two surgical operating rooms.
FOUR KILLED IN FLORIDA
At 5 a.m. EDT (0900 GMT), Matthew's eye was about 20 miles (30 km) south-southeast of Hilton Head, South Carolina. It was moving northward at 12 mph (19 kph), packing 105 mph (165 kph) winds, the U.S. National Hurricane Center said.
It reported wind gusts of 80 mph (130 kph) in Hilton Head and predicted the storm would possibly striking the coast on Saturday morning or afternoon.
"Regardless of whether or not the center makes landfall, hurricane-force winds in the northern eyewall will lash much of the coast of South Carolina," an NHC advisory said.
Matthew sideswiped Florida's coast with winds of up to 120 mph (195 kph) but did not make landfall there. The storm was a Category 2 on the five-step Saffir-Simpson scale of hurricane intensity. Category 5 is the strongest.
There were at least four storm-related deaths in Florida but no immediate reports of significant damage in cities and towns where Matthew swamped streets, toppled trees and knocked out power to about 1 million households and businesses.
About 450,000 were without power in Georgia and South Carolina on Saturday, according to utility companies.
In Florida, two people were killed by falling trees and an elderly couple died of carbon monoxide poisoning from a generator while sheltering from the storm inside a garage.
Hurricane and flash flood warnings extended through Georgia and South Carolina and into North Carolina early on Saturday.
Forecasters warned of flooding as 15 inches (40 cm) of rain were expected to fall in parts of the region along with massive storm surges and high tides.
Several major roadways were inundated in Charleston, South Carolina, local media reported.
Standing water closed both directions of the Interstate 95 highway in Georgia. Some 8 inches (20 cm) of rain had fallen in the Savannah, Georgia area where Matthew downed trees and caused flooding of streets.
WATCH: Storm surge from Hurricane Matthew brings significant flooding to St. Augustine, Florida. pic.twitter.com/upslTTPWy0— NBC Nightly News (@NBCNightlyNews) October 7, 2016
Though gradually weakening, Matthew - which triggered mass evacuations along the U.S. coast - was forecast to remain a hurricane until it begins moving away from the U.S. Southeast on Sunday, according to the NHC.
President Barack Obama and officials urged people to heed safety instructions. Coastal residents were warned that storm surges could still pose a danger by flooding entire neighborhoods even as Matthew departs the region.