Rescuers in boats, helicopters and high-water trucks brought hundreds of people trapped by Hurricane Ida’s floodwaters to safety Monday and utility repair crews rushed in, after the furious storm swamped the Louisiana coast and ravaged the electrical grid in the stifling, late-summer heat.

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

More than 1 million homes and businesses 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 US mainland, pushed through on Sunday.

The damage was so extensive that officials warned it could be weeks before the power grid was repaired.

President Joe Biden met virtually on Monday with Louisiana Gov. John Bel Edwards and Mississippi Gov. Tate Reeves along with mayors from cities and parishes most impacted by Hurricane Ida to receive an update on the storm’s impacts, and to discuss how the Federal Government can provide assistance.

“We are closely coordinating with State and local officials every step of the way,” Biden said.

The administration said more than 3,600 FEMA employees are deployed to Alabama, Florida, Georgia, Louisiana, Mississippi, and Texas. FEMA staged more than 3.4 million meals, millions of liters of water, more than 35,700 tarps, and roughly 200 generators in the region in advance of the storm.

As the storm was downgraded to a tropical depression Monday afternoon and continued to make its way inland with torrential rain, 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 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” – dispiriting news for those without refrigeration or air conditioning during the dog days of summer, with highs forecast in the mid-80s to near 90 by midweek.

“There are certainly more questions than answers. I can’t tell you when the power is going to be restored. I can’t tell you when all the debris is going to be cleaned up and repairs made,” Edwards told a news conference. “But what I can tell you is we are going to work hard every day to deliver as much assistance as we can.”

Local, state and federal rescuers combined to save at least 671 people by Monday afternoon, Edwards said.

In hard-hit LaPlace, squeezed between the Mississippi River and Lake Pontchartrain, rescuers saved people from flooded homes in a near-constant operation.

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

This time, New Orleans appeared to escape the catastrophic flooding city officials had feared.

The city urged people who evacuated to stay away for at least a couple of days because of the lack of power and fuel. “There’s not a lot of reasons to come back,” said Collin Arnold, chief of emergency preparedness.

Also, 18 water systems serving about 255,000 customers in Louisiana were knocked out of service, the state Health Department said.

Four Louisiana hospitals were damaged and 39 medical facilities were operating on generator power, the Federal Emergency Management Agency said. Officials said they were evacuating scores of patients to other cities.

The governor’s office said over 2,200 evacuees were staying in 41 shelters, a number expected to rise as people were rescued or escaped flooded homes. The governor’s spokesperson said the state will work to move people to hotels as soon as possible so they can keep their distance from one another.

“This is a COVID nightmare,” Stephens said, adding: “We do anticipate that we could see some COVID spikes related to this.”

Preliminary measurements showed Slidell, Louisiana, got at least 15.7 inches of rain, while New Orleans received nearly 14 inches, forecasters said. Other parts of Louisiana and Mississippi, Alabama and Florida got 5 to 11 inches.

The Louisiana National Guard said it activated 4,900 Guard personnel and lined up 195 high-water vehicles, 73 rescue boats and 34 helicopters. Local and state agencies were adding hundreds more. Edwards said he decided not to tour hurricane damage by air Monday to add one more aircraft to the effort.

The hurricane twisted and collapsed a giant tower that carries key transmission lines over the Mississippi River to the New Orleans area, causing widespread outages, Entergy and local authorities said. The power company said more than 2,000 miles of transmission lines were out of service, along with 216 substations. The tower had survived Katrina.

The storm also flattened utility poles, toppled trees onto power lines and caused transformers to explode.

The governor said 25,000 utility workers were in the state to help restore electricity, with more on the way. “We’re going to push Entergy to restore power just as soon as they can,” Edwards said.

AT&T said its wireless network in Louisiana was reduced to 60% of normal but was coming back. Many people resorted to using walkie-talkies. The governor’s office staff had no working phones. The company sent a mobile tower to the state’s emergency preparedness office so it could get some service.

Ida’s 150 mph (230 kph) winds tied it for the fifth-strongest hurricane ever to hit the mainland. Its winds were down to 40 mph (64 kph) around midday Monday.

In Mississippi’s southwestern corner, entire neighborhoods were surrounded by floodwaters, and many roads were impassable. Several tornadoes were reported, including a suspected twister in Saraland, Alabama, that ripped part of the roof off a motel and flipped an 18-wheeler, injuring the driver, according to the National Weather Service.

Ida was expected to pick up speed Monday night before dumping rain on the Tennessee and Ohio River valleys Tuesday, the Appalachian mountain region Wednesday and the nation’s capital on Thursday.

Forecasters said flash flooding and mudslides were possible along Ida’s path before it blows out to sea over New England on Friday.