US rescuers on August 30 combed through the “catastrophic” damage Hurricane Ida did to the southern state of Louisiana, a day after the fierce storm killed at least two people, stranded others in rising floodwaters and sheared the roofs off homes.

The city of New Orleans was still mostly without power over 24 hours after Ida slammed into the Louisiana coast as a Category 4 storm, exactly 16 years to the day that Hurricane Katrina made landfall, wreaking deadly havoc.

Two deaths have been confirmed as crews began fanning out in boats and off-road vehicles to search communities cut off by the hurricane.

Images of people being plucked from flooded cars and pictures of destroyed homes surfaced on social media, while the damage in New Orleans itself remained limited.

Ida – which was downgraded to a tropical depression on August 30 – knocked out power for all of New Orleans, with more than a million properties across Louisiana without power, according to outage tracker PowerOutage.US.

According to Louisiana governor John Bel Edwards, the levee system in the affected parishes had “really held up very well, otherwise we would be facing much more problems today”.

In the town of Jean Lafitte, just south of New Orleans, mayor Tim Kerner said the rapidly rising waters had overtopped the 2.3m levees. “Total devastation, catastrophic, our town levees have been overtopped,” Kerner told ABC-affiliate WGNO.

“We have anywhere between 75 to 200 people stranded in Barataria,” after a barge took out a bridge to the island, he said.

Cynthia Lee Sheng, president of Jefferson Parish covering part of the Greater New Orleans area, said people sheltered in their attics.

Several residents of LaPlace, just upstream from New Orleans, posted appeals for help on social media, saying they were trapped by rising flood waters.

“The damage is really catastrophic,” Edwards told NBC’s Today, adding that Ida had “delivered the surge that was forecasted. The wind that was forecasted and the rain.”

President Joe Biden declared a major disaster for Louisiana and Mississippi, which gives the states access to federal aid.

One person was killed by a falling tree in Prairieville, 100km northwest of New Orleans, the Ascension Parish Sheriff’s Office said.

A second victim died while trying to drive through floodwaters in New Orleans, the Louisiana Department of Health tweeted.

Edwards reported on Twitter that Louisiana had deployed more than 1,600 personnel to conduct search and rescue across the state.

US Army Major General Hank Taylor told journalists at a Pentagon briefing that military, federal emergency management officials and the National Guard had activated more than 5,200 personnel in the states of Louisiana, Mississippi, Texas and Alabama.

The National Hurricane Centre issued warnings of storm surges and flash floods over portions of southeastern Louisiana, southern Mississippi and southern Alabama as Ida travels northeast.

The storm system is expected to track across the US all the way to the mid-Atlantic through September 1, creating the potential for flash flooding along the way.

Scientists have warned of a rise in cyclone activity as the ocean surface warms due to climate change, posing an increasing threat to the world’s coastal communities.