KRYMSK, Russia >> On his way into town for another day of flood assistance on Thursday, the leader of the Taman district Cossacks passed a bewildering array of strangers here who were doing the same thing. There were sunburned, tattooed volunteers who traveled from Moscow with the supermodel Natalia Vodianova; others came with white-ribboned opposition leaders; about 150 volunteers from pro-Kremlin youth movements were staying in tents in the center of town.

“Romantics,” scoffed the Cossack chieftain, Col. Ivan V. Bezugly, his gold teeth glinting under a luxuriant handlebar mustache. This absurdity had begun at 3 in the morning after the flood, he said, when a woman called him asking if she could use her flimsy sedan to help retrieve bodies. “They wanted to take a drive from Moscow. But we are in a battle, because Cossack families died.”

The catastrophic flooding of Krymsk has unfolded in an unusually public way over the last week, largely thanks to the power of the Internet. One result has been widespread questioning of the state’s response. Another was a motley stream of young volunteers — officials say more than 2,000 — who have arrived along with trucks full of private donations in a city that was not expecting them.

This activism heralds a jarring change in a country that, throughout the Soviet period, approached disaster response as a military matter and was able to insist on secrecy. When a nuclear reactor melted down in Chernobyl in 1986, for instance, Soviet citizens heard nothing at all about it for three days, and foreign governments did not know until a radioactive cloud was detected over Sweden.

The authorities here, though wary, have allowed the volunteers to stay, and in some cases incorporated them into the relief effort.

“It’s a new story for everyone — for society to help society to solve problems, without any contribution from the government,” said Alyona Popova, a Moscow opposition activist who spent much of last week in Krymsk. “The government can’t control it.”

Activists began arriving in Krymsk a day after a wave more than 20 feet high engulfed low-lying neighborhoods and left 172 people dead, according to the official count. Bloggers and Web-based news services broadcast the fury of local people, who learned that the regional authorities had at least three hours’ warning but made no effort to wake them.

They also published anti-government rumors circulating in the public — that the wave had been intentionally released from nearby reservoirs, for instance, or that compensation was only being paid to those who signed a form saying that they had received a warning. Officials fell back on a classic Soviet tactic, accusing shadowy outsiders of coming into Krymsk to “destabilize the situation.”

“Those who are spreading provocative rumors around the city — they are real enemies,” said the region’s governor, Alexander Tkachev.

The lawmaker Vladimir Zhirinovsky attacked Vodianova, a longtime philanthropist, for “speculating on the tragedy” by traveling to Krymsk. “The dead are not yet buried, and top models like Natalia Vodianova fly in from foreign capitals, prance around, turn on their heels and fly back to the capitals of Europe — London, Paris,” he said Friday.

Still, the volunteers from Moscow and other large cities, some in dreadlocks and yoga pants, have been allowed to stay. One reason may be an unusual pact they made, to refrain from political messages for the length of the cleanup. Opposition activists took off their white ribbons, and — aside from one shipment of aid that came plastered with United Russia stickers — pro-Kremlin groups are not displaying flags or logos.

“Either you are here to work or not,” said Robert Shlegel, 27, a United Russia deputy and former leader of Nashi, a pro-Kremlin youth group. “I don’t see what political questions there can be if a woman needs help drying out a bed or unloading a truck.”

The work is staggering. Piles of refuse along the streets stand as high as rooftops in some places, and saturated walls and ceilings are slowly, sickeningly beginning to buckle. Veterinary services have collected the bodies of more than 43,000 drowned animals, nearly all of them birds, which will be burned and buried in a concrete-lined mass grave to minimize the threat of infectious disease. The euphoria of surviving has given way to something harder.

Lidiya V. Root, 63, said she had begun sobbing hysterically Thursday — for the first time since the storm — while shuttling from one city clerk to another trying to file paperwork.

“I’ve gone crazy, I’ve had some kind of psychological break,” she said. “Last night I slept in a bed — what happiness to have a bed, to put your head down and smell a clean pillow. But as soon as I lay down and closed my eyes I saw the flood, and the roof burning above me.”

If there is a bright spot, she said, it is the volunteers, who drive past her house with such frequency that she now spends much of the day refusing donations. Aside from the Cossacks, who are often recognizable by their mustaches, she has no idea who they are, though license plates suggest that they have come from great distances. Asked what had caused the influx of volunteers, her son, Alexander, offered a simple explanation: “The Internet has developed.”

The work seems to have left deep imprints on some activists. A few days after he returned to Moscow, Danila Lindele, a popular opposition blogger and press secretary, wrote an essay rebutting rumors flying in Krymsk — and expressing regret for reporting that the number of dead may have been as high as 2,000. The activist Popova was surprised to find herself praising the efforts of Shlegel, the United Russia deputy, though she added, “We’re not friends in real life.” She said it was no wonder everyone was having to adjust.

There was also some reassessment going on in the pro-government volunteer camp. Yevgenia Smorchkova, 27, made clear her disgust for rumors circulating in opposition networks. But she had also spent enough time with the angry people of Krymsk to understand where government officials were failing. “About the governor, my personal opinion is that he should be staying out here in one of these tents and talking to people,” she said. “So he’s going to the office at 10 in the morning. What for? What meetings does he need to attend? They need to talk to people more.”

The out-of-town volunteer force — with its tangles of recharging laptops and smartphones — offered a contrast with the Cossacks, the fearsome horsemen who traditionally supported the czars. Cossacks, Bezugly said, “have always defended Russia when she found herself on the edge of the abyss, as in 1917, when the red-bellied Bolsheviks took power.”

Lately, the region’s Cossacks have focused on local matters, like enforcing curfews and driving out a local population of Meskhetian Turks. Before dawn Saturday, Bezugly, the Cossack chieftain, was able to muster 1,000 rescue workers in 90 minutes, an effort that has now shifted to providing aid. One flood victim, he said, had asked the Cossacks for a clean T-shirt and underpants.

“We are warriors, we fight and defend the fatherland, but why not help a person if he appeals to us?” he said. “I’ll tell you what: Cossacks, not just the Taman division but the entire Kuban Cossack army, began to gather on their territory clothing, food, blankets, pillows and everything that is needed.”