Hurricane Milton moves into Atlantic after wreaking havoc in Florida

A weakened but still dangerous Hurricane Milton was exiting Florida early Thursday, after flooding streets and homes, toppling trees and power lines, and knocking power out to millions.

Milton slammed into the west coast of Florida on Wednesday evening as a Category 3 hurricane packing winds of up to 193 kilometres per hour, the US National Hurricane Center said, before losing strength as it barrelled across the midsection of the south-eastern US state.

By the time sunrise approached on Thursday, Milton had been downgraded to a Category 1 hurricane as it pushed into the Atlantic Ocean. Its maximum sustained winds were 150 kilometres per hour.

The monster storm system continued to bring heavy rain, destructive winds and flash flooding. US media showed images of night-time streets turning into rivers in the cities of Tampa, St. Petersburg and Sarasota.

Rainfall amounts of 20 to 35 centimetres are expected across central to northern portions of the Florida peninsula on Thursday.

"This rainfall will continue to bring the risk of catastrophic and life-threatening flash and urban flooding, along with moderate to major river flooding," the hurricane agency said.

Milton spawned 19 tornadoes as it approached Florida from the Gulf of Mexico on Wednesday evening. Sheriff Keith Pearson of St. Lucie county was quoted by local media as saying "multiple fatalities" had resulted from the tornado outbreak, but did not give a specific numbers.

Rescue crews and government officials said the full extent of the destruction will not be known until daybreak.