Punishing tornadoes have battered the US state of Louisiana from north to south, killing at least three people and causing widespread damage on buildings, including houses.

The storms barrelled eastwards on Wednesday after killing a mother and son in the northwestern part of the state a day earlier. The system spun off a suspected tornado that killed a woman on Wednesday in southeast Louisiana’s St Charles Parish and another that pummelled parts of New Orleans and neighbouring Jefferson and St Bernard parishes – including areas badly damaged by a tornado in March.

A tornado struck New Iberia, Louisiana, slightly injuring five people and smashing out windows of a multistory building at Iberia Medical Center. As night drew on, tornado threats eased in Mississippi, although some counties in Florida and Alabama remained under a severe weather threat.

New Orleans emergency director Collin Arnold said businesses and residences in the city suffered significant wind damage, largely on the Mississippi River’s west bank. One home collapsed. Four people were injured there, he said, adding, “The last word we had is that they were stable.”

Similar damage was reported nearby.

In St Bernard Parish – where the March twister caused devastation – Sheriff Jimmy Pohlman said the latest tornado damage covered a roughly 3.2km (2-mile) stretch. Parish President Guy McInnis said the damage was less than in the March tornado though numerous roofs were blown away or damaged.

Authorities in St Charles Parish, west of New Orleans, said a woman was found dead there after a suspected tornado on Wednesday struck the community of Killona along the Mississippi River, damaging homes. Eight people were taken to hospitals with injuries, they said.

About 450km (280 miles) away, in northern Louisiana, it took hours for authorities to find the bodies of a mother and child missing after a tornado swept away their mobile home o Tuesday in Keithville, south of Shreveport.