Hurricane Felix has made landfall in north-east Nicaragua as a category five storm - the strongest of its kind.
The storm has the potential to cause "catastrophic damage", says the Miami-based National Hurricane Center.
Thousands have been fleeing coastal areas ahead of the storm, but many indigenous people are said to be stranded on the Honduran border.
Felix, with winds of 260km/h (160mph), is the second category five storm to hit the region in less than a month.
It is the first time two category five hurricanes have hit land in a season since 1886, according to the US National Oceanic and Atmospheric Administration.
The NHC had earlier downgraded the storm, but later said it had strengthened again.
The NHC said the storm could dump up to 30cm (12in) of rain in isolated parts of northern Honduras and north-eastern Nicaragua, possibly bringing flash floods and mudslides.
Second hurricane
At 1200 GMT on Tuesday, the eye of the hurricane was located on the coast west of or very near Punta Gorda, Nicaragua, about 15km (10 miles) north-north-east of Puerto Cabezas and moving westward at 16mph (26km/h).
The Associated Press news agency quoted a local official in Puerto Cabezas, Lumberto Campbell, who gave an interview to local radio station Radio Ya describing the effect as the hurricane hit:
"The wind is terrible. There's a roaring when it pulls the roofs off the houses," Mr Campbell was quoted as saying.
"There's no electricity because all the posts that hold up the cables have fallen down.
"The metal roofs come off like shaving knives and are sent flying against the trees and homes," he said before the telephone line went dead.
Meanwhile, Tropical Storm Henriette has reached hurricane strength as it heads for Mexico's Baja California peninsula.
It caused landslides in the Mexican city of Acapulco at the weekend that killed six people.
The storm is currently 185km (115 miles) south-east the peninsula and is expected to hit on Tuesday afternoon.
Flooding fears
Hurricane Felix developed in the Caribbean just two weeks after Hurricane Dean killed 18 people in the region.
Nicaraguan President Daniel Ortega has decided to cut short a visit to Panama to lead emergency efforts.
Hundreds of tourists have been evacuated from the islands of Honduras, while both Honduras and Nicaragua have been evacuating Miskito Indians who live along the coast on either side of the border.
But there are reports of transport shortages, and many of the indigenous population are thought to be stranded.
A storm surge of six metres (18 feet) above normal levels would be highly dangerous for those living in the isolated coastal swamps.
"There's nowhere to go here," teacher Sodeida Rodriguez, 26, told AP news agency.
In Belize, people were said to be stocking up on emergency supplies and boarding up windows.
On Sunday, Felix struck Aruba and two of the Netherlands Antilles islands near Venezuela - Bonaire and Curacao - but damage appeared slight.
The sixth named storm of the Atlantic hurricane season, Felix demolished a concert venue when it hit Grenada on Saturday.
The Atlantic hurricane season is expected to peak on 10 September.
Article first appeared on the BBC Website|