As a torrential rain poured from the sky last Sunday, Keri Henry sat in her snug West University Place living room nervously checking Facebook. Floodwaters were rising, emergency lines were jammed, and people were posting desperate pleas for help: "Two elderly people trapped in a one story on their kitchen counters since noon." "Seven people trapped in second floor."

Henry grabbed a notepad and began scratching down details, thinking she would connect the people in trouble with other Facebook users offering boats and high-water vehicles. Within hours, the 36-year-old freelance food stylist was running a one-woman command center from her sofa.

"I see some people commenting on one post and other people commenting on another post, and it just clicked," Henry said. "I had no idea what I was doing but no choice except to do it."

Henry was part of an unprecedented do-it-yourself relief effort that came to define Hurricane Harvey. After the storm blew into Houston, a remarkable network of boat owners with smartphones, worried neighbors with laptops and digital wizards with mapping software popped up to summon and support an army of Good Samaritans who motored, rowed and waded into dangerous waters to save family, friends and total strangers.

The "We the People" response seemed distinctly Texan, an outgrowth of the state's almost genetic disinclination to rely on the government for anything — and in some cases, resolute willingness to defy it. Just as some Texans defied mandatory evacuation orders ahead of the storm, many rescuers ignored repeated official warnings to stay off streets flooded with treacherous and fast-flowing waters.

[Why Houston didn’t order an evacuation before Harvey]

Texas officials, in turn, repeatedly emphasized the importance of personal responsibility. They warned people not to call 911 unless their life was in immediate peril. The top elected official in Tyler County, northeast of Houston, told people not to expect a rescue if they defied evacuation orders. His subtle-as-buckshot words on Facebook: "GET OUT OR DIE!"

Across Southeast Texas, police, firefighters, the National Guard, the Coast Guard and other agencies responded with immense force. But in a storm of Harvey's sheer monstrousness — hundreds of miles across, lingering for days with bucketing rain that swallowed roads and initially kept rescue aircraft grounded — no government response could ever have been enough.

So ordinary people took up the challenge.

"The thing that's been completely different from anything I've ever seen is the way the community has responded. I can't explain to you how awesome it has been," said Houston Police Capt. Yasar Bashir, who stood in a West Houston neighborhood last week watching a volunteer flotilla of boats rescuing victims.



Keri Henry decided to take action when she saw her Houston neighbors being inundated by flood waters last week. Sitting in her living room using her laptop, her iPhone and social media, Henry formed a one-woman command center that would go on to rescue hundreds of flood victims. (Courtesy of Vernon Henry)

Police were working nonstop, "but we can't do it all," Bashir said. "It's because of the citizens that we were able to get everyone out."

The citizen rescue campaign was made possible by technology that didn't exist in 2005 when Hurricane Katrina devastated New Orleans. Then, people listened to AM radio for news and organized rescues by ham radio or by calling reporters, who posted their cries for help on local news blogs.

In 2007, Apple introduced the iPhone, accelerating the rise of social media. Today, more than three-quarters of Americans carry a smartphone in their pocket, according to the Pew Research Center. Harvey is the largest natural disaster to play out in the United States since the dawn of this hyper-connected era.

Because Harvey's strongest winds hit the Texas coast far to the south, near Corpus Christi, Houston didn't suffer the blanket power outages that hit New Orleans during Katrina. As a result, in more places than not, cellphones worked, laptops stayed charged and people could log in to neighborhood Facebook groups and message boards, Twitter, Instagram, Nextdoor and Snapchat.

Rescuers also relied heavily on Zello, a free "walkie-talkie" app that has become popular among activists in conflict zones around the world. The app works on cellphone data plans or WiFi and was designed to operate in places where signals are weak, making it particularly useful in disaster areas. It allows victims and rescuers to post voice messages to specific channels, such as "The Cajun Navy" and "Harvey Animal Rescue."

Bill Moore, chief executive of Zello, a start-up based in Austin, said the app has seen a 20-fold increase in usage in Houston since Harvey hit.

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Houstonians also improvised their own digital tools as the floodwaters rose. Three buddies created the website "Houston Harvey Rescue," according to the site, "in under 3 hours, in a leaky office, with intermittent power, [and] a 2 GB server." The site allowed users to drop a pin on a Google map to alert rescuers to people in trouble. The color of the pin could be changed to indicate the degree of urgency, and the pin could be removed when the rescue was completed, giving rescuers a real-time view of needs across the city.

The site, which claims credit for "over 7,600 active rescues," was no longer operational on Saturday. "Long story short: We aren't needed anymore," read a post from its three creators, Matthew Marchetti, Nate Larson, and Oliver Carter. "Houston saved Houston by open sourcing its own rescue."

Even Texas National Guardsmen sometimes found their cellphones more useful than radios, which have limited range. During patrols this week, soldiers said Facebook became a vital tool for receiving civilian reports of people in need of rescue. Spc. Justin Snow said a responding unit found and rescued dozens of people trapped in a flooded building from a Facebook post.

"Hats off to Google Maps and dropping pins on iPhone," Snow said.

There were the inevitable wild goose chases. In Port Arthur on Thursday, a Facebook post said a rescuer had been electrocuted in the Montrose subdivision. Firefighters rushed out but found no one — one of dozens of false reports.

"Social media has allowed us to process so much information. But it's almost information overload," said Shawn Boudreaux, vice president of Cajun Navy Relief, a volunteer rescue operation, from the command post in Lake Charles, La. "We have trolls. We have hoaxes."

The information overload also led at times to volunteer overload, and some would-be citizen rescuers were turned away from areas where there were already too many boats in the water. The Texas Department of Public Safety reported having to rescue some overeager but undertrained volunteers whose boats overturned in the swift current.

Still, for the most part, the improvisational effort was successful.

When Andrew Brenneise saw his West Houston neighborhood flooding at a ferocious pace last Saturday, his first thought was Facebook Live. He pulled out his smartphone in the punishing rain and pleaded for volunteers with boats.

Forty-five minutes later, the first truck arrived with a boat on a trailer. Then 10 more. Then 20. Then Brenneise had a flotilla of fishing boats, kayaks, canoes and flat-bottomed skiffs which, over the next six days, rescued hundreds of people and animals.

"This is who we are," said Brenneise, 31, a business development manager at a chemical company. "The police and firefighters can't be everywhere, so the community has to step in and take control."

[President Trump returns to Texas]

Tanner Montgomery, 39, a real estate agent, and two friends drove three hours from San Antonio with a canoe on a trailer to help in Brenneise's neighborhood, known as Westchase, where tree-lined streets of elegant homes were threatened throughout the week by releases from nearby Barker Reservoir. Montgomery didn't hear Brenneise's appeal but was alerted through posts on Facebook and Zello, as well as text messages from other volunteers.

"There's way too many people who need help for just the emergency services," Montgomery said. "There's only so many government employees, and there's a lot more of us."

Indeed, emergency services were stretched so thin that police didn't arrive to take control of the rescue operation in Westchase until Thursday. Even then, they had no boats, so they had to hitch rides with the citizen navy, including Montgomery's canoe.

In Memorial, one of Houston's older communities, Denver Courtney and Alex Clamon spent days using their personal boats to rescue stranded neighbors.

"I was sitting there just chewing my fingers off, going, 'I can't watch this and not go help,' " said Clamon, 44, an insurance agent who drove 2½ hours from Palestine, Tex.

"Basically, as a Texan, you know, you're called to duty when something like this happens," added Courtney, 48, an interior designer from Houston. "If you're a hunter and a fisherman and a redneck, man, then you got your boat out here. And if you don't, we don't claim you as a Texan."

Henry launched her personal rescue operation around lunchtime last Sunday from her cozy sectional in West University Place, an independent city near downtown Houston.

"It turns out my Facebook addiction actually had a purpose," she said. With the water rising, she divided the pleas for help into three categories in her notebook: "BABIES." "Elderly." "Families."

On Sunday night, she slept for barely two hours.

"I don't know how many lives I could've saved while I slept," she said. "It was hard to make yourself sleep."

At first, she focused on linking boaters and victims in the closest neighborhoods — Bellaire, Braeswood, Meyerland. But as word of her work spread online, she began receiving tags and private messages from strangers farther away in Memorial and Katy and, eventually, all over Houston.

Boaters arriving from as far away as Florida found their way to her on Facebook as well, seeking guidance about where to deploy. Then Henry linked up with a Houston lawyer, Thomas J. Holmes III, who was commanding his own fleet of boats.

Holmes had something else to offer: online emergency forms. Created through Google Docs, the forms allowed victims and volunteers to provide rescuers with crucial details about their location and health. That information was then uploaded to a master spreadsheet that let rescuers know whether to expect a large family, pets or a victim weighing more than 300 pounds.

"So many random boaters were filling out my Google dispatch form that I realized they could be dispatched almost anywhere there were needs," Henry said. "Our operation just kept growing."

From last Sunday through Thursday, she worked, aided at times by a friend who listened to Zello from her home in Hawaii. At the height of the effort, Henry estimates that she was helping to direct 39 teams of three or four boats each — well over 100 good Samaritans saving an untold number of lives.

"Once I got a few people rescued and things started gaining momentum, I couldn't just look away," she said. "Who was I going to pass the torch to? The 911 dispatch? No way. That wasn't an option."

Correction: An earlier version of this article misspelled Alex Clamon's last name. The article has been updated.

Holley reported from Washington. Alex Horton and Arelis Hernández in Houston contributed to this report.