Hurricane Irma prowled toward the Florida mainland on Sunday, where anxious residents waited in dread to be “punched in the face” by the monster storm after it whipped the Keys island chain with fearsome wind gusts.

Six million people — one third of the state’s population — have been ordered to flee the path of the hurricane, which weakened slightly to a Category Three storm as it churned past the Keys, packing maximum winds of 120 miles (195 kilometers) per hour.

“It’s going to be horrible,” Florida Governor Rick Scott said on NBC. “Now we have to hunker down and watch out for each other.” 

Bob Buckhorn, the mayor the low-lying city of Tampa, was more blunt: “We are about to get punched in the face by this storm.”

“We know we are ground zero for this storm. We have avoided it for 90 years but our time has come to be ready,” he said on Twitter.

One of the mightiest hurricanes ever to slam storm-prone Florida, Irma is threatening dangerous storm surges of up to 15 feet (4.5 meters), enough to cover a house, as it collides with the state after sowing devastation through the Caribbean.

In Miami, the storm brought crashing down at least two construction cranes, while the glitzy Brickell neighborhood was flooded. Steven Schlacknam, a 51-year-old visual artist staying in a 37th floor apartment, said the waters were “coming over the sea walls.”

“The wooden pier is basically gone,” he told AFP.

At least 30 deaths are attributable to the storm, including three in Florida. The US victims included a sheriff’s deputy who was killed in a head-on collision early Sunday as she drove home to get supplies after working in a shelter all night.

Although Irma had yet to make landfall on the continental United States, moving slowly at nine miles per hour (15 kilometers per hour), its high winds and rains were impacting all of south Florida by Sunday afternoon, forecasters said.

The storm is currently headed toward the southwestern tip of the state, then up along the coast to Naples, Fort Myers and the densely populated peninsulas of Tampa Bay on Florida’s west coast.

– Key West damage –

Irma closed in on the Florida coast after ripping boats from their moorings, flattening palm trees and tearing down power lines across the Key West island chain popular for fishing and scuba diving.

“There’s absolutely no way anybody can be outside right now,” Maggy Howes, a first responder on Key Haven, said on CNN earlier Sunday. “You would not be able to stand or walk.”

Irma smacked the Keys 57 years to the day that Hurricane Donna hit the same area in 1960, destroying nearly 75 percent of the island chain’s buildings.

A shelter of last resort set up in the Middle Keys city of Marathon was reported to be without power or running water, and surrounded by surging waters.

“Everything is underwater, I mean everything,” Larry Kahn, an editor for local news website FlKeysNews.com, reported from inside.

– Mother delivers baby alone –

On the mainland, emergency services in Miami were sheltering in place, and a dispatcher talked a woman through delivering her own baby on Sunday morning, Assistant Fire Chief Eloy Garcia told the Miami Herald.

At least two towering construction cranes had collapsed downtown, according to residents and details on social media.

Miami, lined with glittering skyscrapers, has about 25 cranes on construction sites of 50 floors or higher, city manager Daniel Alfonso said. 

More than one million Florida homes and businesses were without power, according to utility company Florida Power and Light, which said it had “safely shut down” one of two nuclear reactors at its Turkey Point power plant.

The National Weather Service urged Floridians to keep their shoes on, to take shelter in interior rooms — far from windows — and use helmets, mattresses, pillows or blankets for protection.

Before reaching the United States, Irma smashed through a string of Caribbean islands from tiny Barbuda on Wednesday, to the tropical paradises of St Barts and St Martin, the US Virgin Islands, Puerto Rico, the Dominican Republic, Haiti and the Turks and Caicos.

Terrified Cubans who rode out Irma in coastal towns — after it made landfall Friday on the Camaguey archipelago as a maximum-strength Category Five storm — reported “deafening” winds, uprooted trees and power lines, and blown rooftops.

There were no immediate reports of casualties in Cuba but it caused “significant damage,” and enormous waves lashed the Malecon, Havana’s emblematic seafront, causing seawaters to penetrate deep into the capital, AFP journalists reported.

– Storm surge, tornado risk –

Irma is so wide that authorities were bracing for destructive storm surges on both coasts of Florida and the Keys as Irma follows a path north toward Georgia.

The NHC also warned of tornado risks through Sunday night, with the greatest threat in areas east of the storm’s path.

Businesses on both Florida coasts were shuttered.

MacDill Air Force Base in Tampa, the military installation home to US Central Command, issued mandatory evacuation orders ahead of the storm’s passage early Monday, while the Kennedy Space Center on the east coast was also closed.

In Naples, the city’s chic coastal neighborhoods stood deserted as torrential rain beat down on streets littered with leaves ripped from palm trees.

But Viviana Sierra, who sought refuge at a shelter outside the city together with her dog, parents and brother, was sanguine about the prospect of finding her home destroyed. 

“You can replace material things but your life is very important, so I think it’s better that we stay here,” she said.