Hurricane Milton felled trees, tore roofs off buildings, and flooded streets, leaving residents of the Florida coast surveying a trail of destruction on Thursday, in a state still reeling from another massive storm two weeks earlier.

Over three million Florida homes and businesses were without power after the weather front made landfall as a Category 3 storm on Wednesday near Siesta Key on the US state's western coast.

As the eye of the storm blew past the peninsula, communities were still contending with strong winds, heavy rainfall, and possible flash floods.

Milton triggered tornadoes before its arrival, with unconfirmed reports of multiple fatalities after one twister struck a retirement community on Florida's east coast.

"We had multiple tornadoes touch down here in the Spanish Lakes community and we have lost some life," St. Lucie County sheriff Keith Pearson told WPBF News.

Pearson also posted a video on his department's Facebook page warning residents to seek shelter, showing their "10,000 square-foot red-iron building" that houses police patrol cars torn apart by a tornado.

"The difficulty with the tornadoes is that we don't know where they're going to land," St. Lucie County commissioner Chris Dzadovsky told reporters.

President Joe Biden was briefed on the "initial impacts" of Milton, the White House said, as responses from Democrats and Republicans are likely to be closely scrutinized with just four weeks until the tightly contested US presidential election.

Milton weakened to a Category 1 storm but was still registering powerful winds of up to 85 miles (140 kilometers) per hour on Thursday morning, according to the National Hurricane Center.

At least 3.1 million households and businesses had lost power in the state by late Wednesday, according to tracker poweroutage.us.

The storm tore through the roof of the home stadium of Major League Baseball team the Tampa Bay Rays, exposing the metal railing underneath as large panels were pulled off and sent flying, video footage showed.

Milton is expected to tear inland, with tourist hub Orlando -- home to Disney World, which has closed for the storm -- in its path.

Scientists say extreme rainfall and destructive storms are occurring with greater severity and frequency as temperatures rise due to climate change. As warmer ocean surfaces release more water vapor, they provide more energy for storms as they form.

In cities up and down Florida's western coast, the wind howled furiously and torrential rain fell as people took shelter wherever they could.

In the city of Sarasota, near Siesta Key, gusts of wind blew panes of glass from buildings on the waterfront.

The streets were deserted and trees swayed almost horizontal, while businesses were shuttered and sandbagged.

On a wooden board fixed against a window of an old red brick building, someone wrote: "Be kind Milton."

The airports in Tampa and Sarasota were closed until further notice.

Just before landfall, Florida Governor Ron DeSantis urged state residents who had not evacuated to "stay inside and stay off the roads," adding: "Flood waters and rushing storm surge are very dangerous."

For authorities to convince some people to evacuate was not easy. One example was a Tampa sailor who went viral on TikTok by pointing out that he would not abandon his ship to the storm; he became recognized as "Lieutenant Dan", a name taken from the movie Forrest Gump, where a character decides to face a storm riding the mast of his ship. However, the authorities reported that they managed to evacuate the sailor before Milton's arrival.

© Agence France-Presse By Gerard Martinez with Daniel Stublen in Orlando