Hurricane Milton has ploughed into Florida as a Category 3 storm, bringing misery to a coast still ravaged by Helene, pounding cities with winds of more than 160 km/h after producing a barrage of tornadoes, but sparing Tampa a direct hit.

The storm tracked to the south in the final hours and made landfall on Wednesday (local time) in Siesta Key near Sarasota, about 112km south of Tampa. The situation in the Tampa area was still a major emergency as St. Petersburg recorded more than 410mm of rain, prompting the National Weather Service to warn of flash flooding.

Tropicana Field, the home of the Tampa Bay Rays in St. Petersburg, appeared to be badly damaged. Television images on Wednesday night showed that the fabric that serves as the domed building's roof had been ripped to shreds. It was not immediately clear if there was damage inside the stadium.

More than 2 million homes and businesses were without power in Florida, according to poweroutage.us, which tracks utility reports. The highest number of outages were in Hardee County, as well as neighbouring Sarasota and Manatee counties.

Before Milton even made landfall, tornadoes were touching down across the state. The Spanish Lakes Country Club near Fort Pierce, on Florida's Atlantic Coast, was hit particularly hard, with homes destroyed and some residents killed.

"We have lost some life," St. Lucie County Sheriff Keith Pearson told WPBF News, though he wouldn't say how many people were killed.

The Tampa Bay area has not taken a direct hit from a major hurricane in more than a century, but the storm was still bringing a potentially deadly storm surge to much of Florida's Gulf Coast, including densely populated areas such as Tampa, St. Petersburg, Sarasota and Fort Myers.

The National Weather Service said flash flooding was occurring in the Tampa Bay area, including St. Petersburg, where more than 41cm of rain had fallen.

Heavy rains were also likely to cause flooding inland along rivers and lakes as Milton traverses the Florida Peninsula as a hurricane, eventually to emerge in the Atlantic Ocean on Thursday.

About 125 homes were destroyed before the hurricane even made landfall, many of them mobile homes in communities for senior citizens, said Kevin Guthrie, the director of the Florida Division of Emergency Management.

About 90 minutes after making landfall, Milton was centred about 30km northeast of Sarasota and had weakened slightly with maximum sustained winds of 175km/h, becoming a Category 2 storm, the hurricane center reported. It was moving east-northeast at 26km/h.

Milton slammed into a Florida region still reeling from Hurricane Helene, which caused heavy damage to beach communities with storm surge and killed a dozen people in seaside Pinellas County alone.

Earlier, officials issued dire warnings to flee or face grim odds of survival.

"This is it, folks," said Cathie Perkins, emergency management director in Pinellas County, which sits on the peninsula that forms Tampa Bay.

"Those of you who were punched during Hurricane Helene, this is going to be a knockout. You need to get out, and you need to get out now."

By late afternoon, some officials said the time had passed for such efforts, suggesting that people who stayed behind hunker down instead. By the evening, some counties announced they had suspended emergency services.

Milton was expected to remain a hurricane as it plowed across the state, including the heavily populated Orlando area, through Thursday.

The storm threatened communities still reeling two weeks after Hurricane Helene flooded streets and homes in western Florida and left at least 230 people dead across the South. In many places along the coast, municipalities raced to collect and dispose of debris before Milton’s winds and storm surge could toss it around and compound any damage. Surge was projected to reach as high as 2.7m in Tampa Bay.

The famous Sunshine Skyway Bridge, which spans the mouth of Tampa Bay, closed around midday. Other major bridges also closed.

At a news conference in Tallahassee, Governor Ron DeSantis described deployment of a wide range of resources, including 9000 National Guard members from Florida and other states; more than 50,000 utility workers from as far as California; and highway patrol cars with sirens to escort gasoline tankers to replenish supplies so people could fill up their tanks before evacuating.

"Unfortunately, there will be fatalities. I don't think there's any way around that," DeSantis said.

Heavy rain and tornadoes lashed parts of southern Florida starting on Wednesday morning, with conditions deteriorating throughout the day. Up to 310mm of rain, with up to 460mm in some places, was expected well inland, bringing the risk of catastrophic flooding.

One twister touched down on Wednesday morning in the lightly populated Everglades and crossed Interstate 75. Another apparent tornado touched down in Fort Myers, snapping tree limbs and tearing a gas station's canopy to shreds.

Authorities have issued mandatory evacuation orders across 15 Florida counties with a total population of about 7.2 million people. Officials warned that anyone staying behind must fend for themselves, because first responders were not expected to risk their lives attempting rescues at the height of the storm.

St Petersburg Mayor Ken Welch told residents to expect long power outages and the possible shutdown of the sewer system.

By early afternoon, airlines had cancelled about 1900 flights. SeaWorld was closed all day on Wednesday, and Walt Disney World and Universal Orlando shut down in the afternoon.

More than 60% of gas stations in Tampa and St. Petersburg were out of gas on Wednesday afternoon, according to GasBuddy. DeSantis said the state's overall supply was fine, and highway patrol officers were escorting tanker trucks to replenish the supply.

In the Tampa Bay area's Gulfport, Christian Burke and his mother stayed put in their three-story concrete home overlooking the bay. Burke said his father designed this home with a Category 5 in mind — and now they're going to test it.

As a passing police vehicle blared encouragement to evacuate, Burke acknowledged staying isn't a good idea and said he's "not laughing at this storm one bit".