At least six people are known to have died as Hurricane Wilma pounds Mexico's Yucatan Peninsula for a second day.
Tens of thousands of people, many of them foreign tourists, are riding out the storm in overcrowded shelters.
The slow-moving storm has sent waves surging over hotels in the resort of Cancun, wiped out electricity supplies and flattened hundreds of homes.
Meanwhile, tropical storm Alpha has formed in the Caribbean, making 2005 the busiest hurricane season on record.
Forecasters said Wilma had weakened but was expected to intensify as it slowly heads towards Florida's west coast.
Officials have ordered 80,000 residents to leave the vulnerable Florida Keys island chain ahead of the storm's arrival late on Sunday or Monday.
Hundreds of thousands of people have also been moved from coastal areas in western Cuba, already lashed by rains and a tornado spun off from Wilma.
Storm surges reached as high as the third storey of some hotels on Saturday, as the hurricane lingered over Cancun.
In the resort town of Playa del Carmen, two people died when a gas tank exploded.
And to the west of the Yucatan Peninsula, a man died after he was crushed under a large branch.
Two more were reported to have been killed on Cozumel island and another died in Cancun when a gust of wind blew out a window.
Hundreds of thousands of tourists and residents are sheltering in schools and gymnasiums around Cancun.
Many have been forced to move to higher floors as waves crash in. Others have sought safety in sturdier shelters as roofs are peeled off and windows shattered.
The force of the waves has also sent sea water crashing into an alligator-infested lagoon.
There have been some reports of looting and police officers have been standing guard outside some of the larger convenience stores.
On the resort island of Cozumel - which took the brunt of the storm on Friday - streets have been flooded and hotel windows shattered.
Playa del Carmen has also suffered severe damage, the town's civil defence chief Moises Ramirez told the AFP news agency.
"Playa is destroyed," he said. "We have water everywhere, all of the power lines are down, we are flooded all over. Playa is just not like this."
Mexico's President Vicente Fox, who is to visit the area on Sunday, sought to reassure both tourists and residents in a televised address.
"Certainly we have been working with the hotels and tourism industry to protect the tourists and the visitors," he said.
"But make no mistake - our priority, our main focus is with our own people, and that's where we want to ensure that things go well."
The US National Hurricane Center (NHC) had downgraded Wilma to a Category-Two storm, packing winds of 100 mph (160km/h) by 0900 GMT.
The peninsula and areas of western Cuba can expect 25 to 38cm (10 to 15in) of rain by Sunday, the NHC has warned.
The formation of Tropical Storm Alpha, which threatens flooding for Haiti and the Dominican Republic, makes this year's Atlantic hurricane season the most active since 1933.
It is the first time the NHC has had to resort to using the Greek alphabet to name a storm, after all 21 names pre-assigned for storms this year were used up.
The hurricane season still has five weeks to run. It ends on 30 November.
Satellite image shows Hurricane Wilma (left) and Tropical Storm Alpha (bottom right) at 2100 GMT on Saturday