HOUSTON, July 10, 2024 (BSS/AFP) - At least eight people were killed in the southern United States after storm Beryl felled trees and caused heavy flooding, before being downgraded to a post-tropical cyclone on Tuesday.

In the aftermath, as millions in the Houston area remained without power and were sweating under a heat advisory, President Joe Biden said sweltering temperatures were "the greatest concern."

Beryl entered Texas from the Gulf of Mexico as a Category 1 hurricane early Monday. At least seven people died in the storm in Texas, with another person killed in neighboring Louisiana, authorities said.

The total death toll from the record-breaking hurricane has risen to at least 18 after it tore through the Caribbean last week -- at one point as a Category 5 hurricane, the highest recordable strength.

Some 2 million households in Texas were without electricity Tuesday evening due to damaged power grids, even as temperatures were forecast to reach 106 degrees Fahrenheit (41 degrees Celsius) with humidity factored in.

"The greatest concern right now is the power outages and extreme heat that is impacting Texans," Biden said in a statement.

Another 14,000 homes were also without power in Louisiana, according to the poweroutage.us tracker.

Air-conditioned shelters for residents were set up while crews worked to restore service.

Beryl weakened Tuesday and was heading northeast through the midwest United States with 30 miles (45 kilometers) per hour winds, the US National Hurricane Center said, warning it could still generate flooding and tornadoes.

The sprawling city of Houston, home to 2.3 million people, was badly battered by hurricane-strength winds and flooding.

Harris County Sheriff Ed Gonzalez said on X that a 53-year-old man and 74-year-old woman had died in separate incidents of trees falling on houses.

Later, Houston Mayor John Whitmire told a press conference that one person died after a lightning strike possibly ignited a fire, while a police department employee died in floodwaters on his way to work.

Meanwhile in Louisiana, one death was announced by the Bossier Parish sheriff's office, also caused by a tree falling on a home.

- 'Very rare' -

Rose Michalec, 51, told AFP that Beryl blew down fences in her south Houston neighborhood.

"It's quite a bit of damage... It's more than we expected," she said.

In downtown Houston, several areas were inundated, including the park where 76-year-old Floyd Robinson usually walks.

"I'm seeing more of this kind of damaging water than I've ever seen before," the lifelong Houston resident told AFP.

"This is just the beginning of July and for us to have a storm of this magnitude is very rare."

Along the Texas coastline, several waterfront homes and buildings had their roofs torn off by the wind.

- Path across Caribbean -

Beryl first slammed Grenada and Saint Vincent and the Grenadines as a Category 4 storm, before plowing past the Cayman Islands and Jamaica, and at one point strengthening to Category 5.

It hit Mexico on Friday, flattening trees and lampposts and ripping off roof tiles.

Beryl left a deadly toll with three deaths in Grenada, two in St. Vincent and the Grenadines, three in Venezuela and two in Jamaica.

It is the first hurricane since NHC record-keeping began to reach the Category 4 level in June, and the earliest to hit the highest Category 5 in July.

Beryl is also the earliest hurricane to make landfall in Texas in a decade, according to expert Michael Lowry.

It is extremely rare for such a powerful storm to form this early in the Atlantic hurricane season, which runs from early June to late November.

Scientists say climate change likely plays a role in the rapid intensification of storms such as Beryl because there is more energy in a warmer ocean for them to feed on.