This photo shows buildings partially submerged in water in Cameron, Louisiana, on Aug 27, 2020 after Hurricane Laura's landfall. (BILL FEIG / THE ADVOCATE VIA AP)

LAKE CHARLES - Hurricane Laura tore through Louisiana on Thursday, killing six people and flattening buildings across a wide swatch of the state before moving into Arkansas with heavy rains.

Laura's powerful gusts uprooted trees - and four people were crushed to death in separate incidents of trees falling on homes. The state's department of health said late Thursday that there were two more fatalities attributed to the hurricane - a man who drowned while aboard a sinking boat and a man who had carbon monoxide poisoning caused by a generator in his home.

In Westlake, a chemical plant caught fire when hit by Laura, and the flames continued to send a chlorine-infused plume of smoke skyward nearly 24 hours after landfall.

This was the most powerful storm to ever make landfall in Louisiana. It's continuing to cause damage and life-threatening conditions.

John Bel Edwards, Governor of Louisiana, US

Laura caused less mayhem than forecasts predicted - but officials said it remained a dangerous storm and that it would take days to assess the damage. At least 867,000 homes and businesses in Louisiana, Texas and Arkansas remained without power on Thursday afternoon.

"This was the most powerful storm to ever make landfall in Louisiana," Governor John Bel Edwards said at a news conference. "It's continuing to cause damage and life-threatening conditions."

ALSO READ: Hurricane Laura weakens after 'catastrophic' landfall in Louisiana

Laura's maximum sustained winds of 241 kph upon landfall easily bested Hurricane Katrina, which sparked deadly levee breaches in New Orleans in 2005, and arrived with wind speeds of 201 kph.

The NHC said Laura's eye had crossed into southern Arkansas late Thursday afternoon and was heading to the northeast at 24 kph. The storm could dump 178 mm of rain on portions of Arkansas, likely causing flash floods.

Laura was downgraded to a tropical depression by the National Hurricane Center (NHC) at 10 pm, and the forecaster said it will move to the mid-Mississippi Valley later on Friday and then to the mid-Atlantic states on Saturday.

A building is left damaged by Hurricane Laura, in Lake Charles, Louisiana, Aug 27, 2020. (BILL FEIG / THE ADVOCATE VIA AP)

Chemical plume

Laura's howling winds leveled buildings across a wide swath of the state and a wall of water that was 15 feet high crashed into tiny Cameron, Louisiana, where the hurricane made landfall around 1 am.

A calamitous 20-foot storm surge that had been forecast to move 64 km inland was avoided when Laura tacked east just before landfall, Edwards said. That meant a mighty gush of water was not fully pushed up the Calcasieu Ship Channel, which would have given the storm surge an easy path far inland.

Tropical-force winds were felt in nearly every parish across Louisiana - and Edwards warned that the death toll could climb as search and rescue missions increase.

READ MORE: Thousands evacuate as dueling storms take aim at US Gulf Coast

A building is left damaged by Hurricane Laura, in Lake Charles, Louisiana, Aug 27, 2020. (BILL FEIG / THE ADVOCATE VIA AP)

Cleanup begins

Residents of Lake Charles heard Laura's winds and the sound of breaking glass as the storm passed through the city of 78,000 with winds of 137 kph and gusts up to 206 kph in the hour after landfall.

National Guard troops cleared debris from roads in Lake Charles on Thursday afternoon. There were downed power lines in streets around the city, and the winds tipped a few semi-trucks onto their sides.

The windows of the city's 22-storey Capital One Tower were blown out, street signs were toppled and pieces of wooden fence and debris from collapsed buildings lay scattered in the flooded streets, video footage on Twitter and Snapchat showed.

Lake Charles resident Borden Wilson, a 33-year-old pediatrician, was anxious about his return home after evacuating to Minden, Louisiana.

"I never even boarded up my windows. I didn't think to do that. This is the first hurricane I've experienced. I just hope my house is fine," he said in a telephone interview.