NEW ORLEANS (AP) — Rescuers set out in hundreds of boats and helicopters to reach people trapped by floodwaters Monday, and utility repair crews rushed in, after a furious Hurricane Ida swamped the Louisiana coast and made a shambles of the electrical grid in the sticky, late-summer heat.

People living amid the maze of rivers and bayous along the state’s Gulf Coast retreated desperately to their attics or rooftops and posted their addresses on social media with instructions for search-and-rescue teams on where to find them.

More than 1 million customers in Louisiana and Mississippi — including all of New Orleans — were left without power as Ida, one of the most powerful hurricanes ever to hit the U.S. mainland, pushed through on Sunday and early Monday before weakening into a tropical storm.

As the storm continued to make its way inland with torrential rain and shrieking winds, it was blamed for at least two deaths — a motorist who drowned in New Orleans, and a person hit by a falling tree outside Baton Rouge.

But with many roads impassable and cellphone service knocked out in places, the full extent of its fury was still coming into focus. Christina Stephens, a spokesperson for Gov. John Bel Edwards, said that given the level of destruction, “We’re going to have many more confirmed fatalities.”

The governor’s office said damage to the power grid appeared “catastrophic.” And officials warned it could be weeks before power is fully restored, leaving multitudes without refrigeration or air conditioning during the dog days of summer, with highs forecast in the mid-80s to close to 90 by midweek.

The hurricane blew ashore on the 16th anniversary of Katrina, the storm that devastated New Orleans in 2005 and was blamed for 1,800 deaths.

“For the most part, all of our levees performed extremely well — especially the federal levees — but at the end of the day, the storm surge, the rain, the wind all had devastating impacts,” Edwards said. “We have tremendous damage to homes and to businesses.”

When daylight came, the streets of New Orleans were littered with branches and some roads were blocked. But there were no immediate reports of the catastrophic flooding city officials had feared.

“I had a long miserable night,” said Chris Atkins, who was in his New Orleans home when he heard a “kaboom” and all the sheetrock in the living room collapsed. A short time later, the whole side of the living room fell onto his neighbor’s driveway.