They were unforgettable pictures: wild animals roaming the streets of Tbilisi last month, after escaping from the city’s flood-stricken zoo. The Georgian capital had become an urban jungle. The surreal sight of a giant African hippo lumbering past brightly lit shops and snacking on roadside greenery before being tranquilised and gingerly ushered back inside the devastated zoo complex made front pages worldwide. These were almost biblical scenes of bears fighting to stay above the floodwaters, or mud-caked lions and tigers drowned or shot dead, although there was no ark to come to the rescue.

Some Georgians were annoyed at the way the animals’ plight had captured the world’s attention; it was also the city’s worst human disaster in years. The flash flood that struck on 13 and 14 June claimed at least 19 lives. Three people are still unaccounted for and dozens were left homeless. Four days after the flood, an escaped tiger killed another man. “It was a tragedy beyond my imagination,” says zoo director Zurab Gurielidze, who only narrowly escaped the surge himself.

Three weeks on, all the animals are now accounted for – including the last missing tiger, whose body was found a few days ago. But the zoo has lost more than 300 animals, either drowned, or shot dead by police – over half its pre-flood population. Exhausted staff are mourning three colleagues who lived on site and were killed in the deluge.

A hippopotamus walks along a flooded street in Tbilisi after zoo animals escaped their enclosures following heavy flooding in the Georgian capital. Guardian

With many cages obliterated, staff have had to come up with imaginative solutions for housing the remaining animals. One of the crocodiles is in the penguin enclosure – a hole in the viewing glass now a handy short cut into the pool. The eight surviving penguins – from a batch transferred last year from Torquay zoo in Devon – are having to make do with a smaller cage next to the birds of prey.

Workers are trying to clear enough of the site to meet Gurielidze’s ambitious target of reopening by 1 August. “If we can’t do that, definitely by 1 September,” he says. “The zoo is a public service. We must be open.”

The immediate priority, says zoo spokeswoman Mzia Sharashidze, is finding around £250,000 to build a proper shelter for the now-famous hippo before winter comes. The animal, named Beggi, is currently squatting in part of the elephant pen. “It can’t survive the cold there,” she says.

Longer term, the plan is to raise enough funds to move to a new, larger site on the edge of Tbilisi. But relocation costs have been put at £15m at least – a big sum for Georgia – and the coalition government has not yet said whether it will foot the bill.

It is still reeling from criticism of its handling of the disaster at the zoo, and what was seen as an attempt to shift the blame on to Gurielidze, zoo director since 2006 and now a hugely popular figure. Hundreds of protesters rallied in his support outside government headquarters after he was called in for police questioning. Many of the demonstrators had been among the thousands of volunteers who turned out to help survivors and clear the wreckage, a moment some activists hoped marked a new awakening among young people in this former Soviet republic.

A white tiger is stretchered away after it was killed by police in Tbilisi. Photograph: Reuters

The unusually heavy storm over Tbilisi on the night of Saturday 13 June took everyone by surprise. Two months of rain fell in just a couple of hours. After a late dinner, Gurielidze and his wife, Dr Natia Kopaliani, decided to check on the animals. They arrived around midnight, he says, by which time the rain had stopped. There were lots of puddles, but otherwise everything seemed fine.

“We went to check on the hyenas and the pigs,” Kopaliani says. “Then, suddenly, there was water all around us. There was no noise, but it was rising so fast. It was terrifying.” The couple ran to their car, but before they could drive away, the water was up to the doors. Gurielidze and Kopaliani got out of the vehicle just in time, the surge flipping it over as they made it to the top of a nearby animal cage. “We kept climbing higher as the water kept rising,” Kopaliani says.

In the small zoo accommodation block below them, their three colleagues never stood a chance. Among them was Guliko Chitadze, a veteran staff member who had recently had her arm amputated after one of the tigers attacked her. She had returned to work that week.

Several hours of unimaginable terror lay ahead for Gurielidze and his wife, marooned on top of one of the tiger cages in his own zoo. He knew the tigers below had escaped, along with many other animals, but in the darkness had no idea where they were. The couple couldn’t call for help because their mobiles had been washed away. Police sent to the zoo eventually heard their shouting, but wouldn’t venture inside because of the threat of attack. “Then we heard them shooting animals,” says Kopaliani. It was only when the waters began to recede that zoo colleagues and rescue workers finally helped them to safety.

Tbilisi zoo director Zurab Gurielidze holds two tiger cubs at the zoo, before disaster struck. Photograph: David Mdzinarishvili/Reuters

Upstream of the zoo, dozens of houses had been washed away while residents were asleep. It’s now thought that a landslide triggered by the rain blocked the Vere river just outside Tbilisi. When this temporary dam then burst under the weight of water, it sent a wave of mud, rock and tree trunks down into the city. The head of Georgia’s Orthodox church, Patriarch Ilia II, said the flood was punishment for the “sin” of the country’s former communist rulers, adding that they had paid for the zoo by melting down church crosses and bells.

Others blamed what they saw as government incompetence and poor emergency planning that left residents with no warning of what was coming. Even as the waters were rising around the zoo, the road alongside it remained open, trapping drivers in their cars.

Activist and environmental campaigner Nick Davitashvili says planning has taken a back seat during Georgia’s post-Soviet evolution. “It all used to be done in Moscow,” he says. “Thankfully, the USSR has gone, and a lot has changed, but no one knows how to plan properly here yet.”

The government says it could never have predicted such a disaster, though it is now promising an early warning system along the river. “We did everything we could, deploying the emergency services as soon as we knew of the flooding, and we saved a lot of lives,” said a spokesman for prime minister Irakli Garibashvili.

Questions were asked about why police deployed at the zoo didn’t have tranquilisers and shot so many animals. “They gunned down animals without even attempting to save them,” says Tina Chavchanidze, chair of the Tbilisi-based Committee for Animal Rights, who has called for better training for police units. The government says that, with the potential threat to human life, police couldn’t take a risk.

A keeper walks past dead bears at the zoo in Tbilisi. Photograph: David Mdzinarishvili/Reuters

Even Beggi the hippo – now the symbol for a host of fundraising efforts – only narrowly escaped being shot, after volunteers organised an impromptu rescue. After hearing of the disaster, one of Gurielidze’s longtime expedition partners, Levan Butkhuzi, rushed to help. “It was chaos when I got there,” he says, “and no one seemed to be in charge.” When the runaway hippo was spotted, he and others persuaded the police to give them a chance to save it, pointing out there were now TV cameras around.

With the zoo’s tranquiliser stock inaccessible, Butkhuzi called in a friend who runs a bear conservation project two hours outside Tbilisi, telling him to bring all the drugs he had. Hippos are notoriously aggressive, and Beggi weighs more than two tonnes, so it was an agonising wait. Butkhuzi admits they took a further risk when the bear expert arrived, using only a half-dose in the tranquiliser dart. If we had put the hippo to sleep, it would have been impossible to move it,” he says.

When, four days after the flood, a tiger killed a warehouse cleaner nearby, officials argued that their actions had been vindicated. But it was also hugely embarrassing, coming after an announcement from the prime minister that all the animals had been accounted for.

Many here in Georgia condemned the foreign media’s focus on the zoo. The stories that dominated Georgian coverage were of a pregnant woman being swept from her husband’s arms by the surge, and the drowning of Zurab Muzashvili, a 36-year-old emergency worker, after he had saved seven people. But on one of several visits to families hit by the disaster, I was treated instead to typical Georgian hospitality. “I’m so sorry I can’t invite you inside for tea,” apologised Ilia Mosikashvili, pointing towards her house, half of which now hangs over a precipitous drop after the ground beneath was washed away.

Many Georgians were also touched by the fate of the animals. Thousands have signed a petition calling for the zoo site to be renamed Shumba park, after the young white lion cub shot by police. The huge volunteer turnout was a moment of “great unity”, says Davitashvili, who helped to coordinate the effort along with fellow members of the Tbilisi Guerilla Gardeners movement. More than 20,000 people signed up to its Facebook page – although a week after the flood the site was mysteriously blocked, with many suspecting an effort to undermine this sudden burst of people power.

Some predict this more activist mood may simply subside like the floodwaters. But, if nothing else, the protests and open criticism were a sign of democracy becoming increasingly entrenched. With elections next year, the government was rattled, seeking to blame the solidarity protest for the zoo director on the main opposition party. And Davitashvili and other activists believe more Georgians “are picking up on the idea that it’s up to them to stand up for issues they care about.”

Back at the zoo, Sharashidze puffs nervously on a cigarette. “There used to be only two smokers here,” she says. “Now almost all of us are.” But they have had some good news since the disaster. A rare Caucasian red deer, which the zoo is helping to protect as part of a WWF-backed conservation project, has just given birth to a young female calf. Gurielidze has named her “Pyrra”’, after one of only two survivors of the giant flood in Greek mythology ordered by the god Zeus.