Updated at 4 p.m. ET
Just days into one of the biggest storms to hit the U.S. in decades, authorities have rescued thousands of people in Houston alone. And as floodwaters from Hurricane Harvey, now a tropical storm, continue to rise across southeast Texas and neighboring Louisiana, officials expect that still thousands more evacuees will need to be sheltered in the days to come.
Several deaths have been reported, but the exact number remains unclear. A spokesperson with the Harris County Institute of Forensic Sciences told NPR six deaths are suspected of being related to flooding, though final determinations will not be made until autopsies are finished.
"This is a landmark event," Federal Emergency Management Agency Director Brock Long said at a news conference Monday. In fact, it has been such a landmark event — with more than 3 feet of rain having already hit some regions — the National Weather Service has even had to revise its traditional methods of representing storms "in order to effectively map it."
So how does one respond to a catastrophe of such historic proportions?
For authorities, that has meant summoning a rescue and evacuation effort nearly as massive. "The goal is rescue," Houston Mayor Sylvester Turner told reporters Monday. "That's the major focus for the day."
Here's how that rescue effort is taking shape, sketched in a few telling — and staggering — numbers.
Houston Police Chief Art Acevedo told reporters Monday that officers have rescued roughly 2,000 people in the city — out of about 4,000 water-related calls for assistance — since the storm came ashore Friday evening.
That includes ...
... rescues over a 12-hour span since midnight on Monday. But that number does not include the 185 critical rescue requests in the city still outstanding as of midday.
Police hope to work through that backlog of requests by nightfall, because they say their boats are not properly equipped to conduct rescue operations in the dark.
Many of those people who required rescue will also require a place to stay — which brings us to ...
"Once we move them, we're able to extract them from different areas and rescue them, we've got to get them into shelters," Long said Monday. "This shelter mission is going to be a very heavy lift. We're anticipating over 30,000 people being placed in shelters temporarily."
Already 5,500 people are staying in shelters in Houston, and Turner only expects that number to rise in a greater metro area of some 6.5 million people.
Even in San Antonio, which was largely saved from the worst of the storm's impact, Mayor Ron Nirenberg told NPR more than 1,000 evacuees have been sheltered — a number he expects to "increase sharply," as well.
"No one will be turned away," he said. "We will do whatever is necessary. The capacity is whatever is needed."
Still, authorities have been struggling to supply those evacuees. The Red Cross initially was unable to get their trucks to one shelter, and those evacuees, without food, had McDonald's breakfast Sunday morning.
But there might not be such scarcity for long. Vice President Mike Pence told KTRH the federal government has shipped out more than 1.2 million meals and a million liters of water.
Texas Gov. Greg Abbott activated the state's entire National Guard on Monday, saying roughly 12,000 guard members will be deployed to respond to Harvey. Initially, about 3,000 national and state guard members had been deployed.
"It is imperative that we do everything possible to protect the lives and safety of people across the state of Texas as we continue to face the aftermath of this storm," Abbott said in a statement.
The governor noted that the guardsmen will be collaborating with FEMA and federal troops to "assist in the efforts already underway."
The U.S. Coast Guard has also been active in the response, deploying at least eight helicopters — and requesting 11 more from across the country — to conduct rescues. They say they have already rescued 100 people from the air.
"Every Coast Guard asset available" is being used to respond, Coast Guard Commandant Adm. Paul Zukunft said. "But," he cautioned, "there are conditions where it is just not safe to fly."
All told, Pence said Monday there are more than 8,500 federal personnel on the ground in the area to help state and local officials, who are leading the rescue efforts.
Even officials with the Mexican government have offered Texas assistance in its recovery from the storm, Abbott said at a news conference Monday.
The extensive state and national response was motivated partly by the immense breadth of the storm's effects, apparent in the next number.
Long expects as many as 50 counties in Texas to be affected in some form by the storm's floodwaters, a situation that he says has demanded the agency "help bolster the efforts to do swift water rescue, search and rescue over a huge county jurisdiction."
Eighteen of those counties have been granted a federal disaster declaration, a move that triggers FEMA's support.
Harris County Judge Ed Emmett, the top administrator in the county home to Houston, noted just what the size of the storm means for local officials.
"One of the issues, of course, that makes this situation even worse is all of the surrounding counties are experiencing their own difficulties," he said at a news conference Monday, "so we're not in this alone, but we can't really help each other."
And the size of the storm means it's not just Texas that must bear its blows. Some 15-25 inches of rainfall are expected in southwest Louisiana, and President Trump declared an emergency in the state on Monday morning.
By the time the region emerges from Harvey's aftermath, Long expects nearly half a million people will have requested help. Pence said 22,000 have already registered for disaster assistance.
And it's unlikely that aftermath will lift anytime soon.
"You've got rivers and bayous that are going to be reaching crest stage later in the week in and around Houston," NPR's Debbie Elliott pointed out, citing the head of the National Weather Service. "The floodwaters are going to be slow to recede. They're going to persist."
"This is going to take us months, years to get back to normal," Emmett said, "and so any help that people can send, we would certainly appreciate that."