At least 14 people including Ukraine’s interior minister, Denys Monastyrsky, and other senior officials have been killed after a helicopter crashed by a kindergarten in a suburb of Kyiv. A number of children at the school in Brovary were among the casualties after debris hit the building. The most recent update, on Wednesday afternoon, suggested one child had been killed, after previous reports that the number was at least three. Officials gave no immediate account of the cause of the crash. The SBU state security service said it was investigating possible causes including a breach of flight rules, a technical malfunction and the intentional destruction of the helicopter. Ukraine’s president, Volodymyr Zelenskiy, described the crash as “a terrible tragedy” on a “black morning”. “The pain is unspeakable,” he wrote on Telegram. Monastyrsky, who was responsible for the police and security in Ukraine, is the most senior Ukrainian official to die since the war began. The national police chief, Ihor Klymenko, said Monastyrsky was killed along with his deputy and other senior ministry officials. The regional governor said 18 people had been killed, but emergency services later announced a death toll of 15 and said 25 others had been injured, including 10 children. “There were children and … staff in the nursery at the time of this tragedy. Everyone has now been evacuated. There are casualties,” the Kyiv regional governor, Oleksiy Kuleba, wrote on Telegram. “For now, we are considering all possible versions of the helicopter crash accident,” said Ukraine’s prosecutor general, Andriy Kostin, amid suggestions it could take several days before the cause of the crash is established. The helicopter, a Super Puma supplied by France, appears to have been travelling to a frontline area in foggy conditions when it came down in an area where there are a number of tall buildings. According to some claims, the crash occurred when the helicopter clipped the kindergarten through pilot error, although it was not clear why it was flying so low in a built-up area. One witness said he saw the helicopter approach the neighbouring building from his kitchen window before it fell sharply. At the site of the crash, a Guardian journalist saw a large crater between a residential building and the nursery. The charred, burnt-out engine and tail wing of the helicopter was leaning against the entrance to the residential building, and other parts of the helicopter were strewn between the building and the nursery. Footage from the scene of the crash showed a large area around the kindergarten on fire in the immediate aftermath of the impact, and bodies lying in the street outside. In one picture, the helicopter’s main rotor could be seen embedded in a car roof. Inside the school, classrooms were littered with debris, with windows broken and walls scorched. “We saw wounded people, we saw children. There was a lot of fog here, everything was strewn all around. We could hear screams, we ran towards them,” Glib, a 17-year-old local resident, told Reuters at the scene. “We took the children and passed them over the fence, away from the nursery as it was on fire, especially the second floor,” he said. Klymenko said in a statement that the helicopter had been carrying Monastyrsky and eight others. Klymenko said Monastyrsky’s deputy minister, Yevhen Yenin, and the state secretary, Yuriy Lubkovych, also died in the crash. The investigation was being carried out by the security service of Ukraine, Klymenko said. Ukraine’s first lady, Olena Zelenska, appeared emotional minutes before attending a World Economic Forum session in Davos, Switzerland. “Another very sad day today – new losses,” she said. The forum president, Børge Brende, requested 15 seconds of silence after opening the session, to honour the Ukrainian officials killed in the crash. It came four days after a Russian missile strike on an apartment building in south-east Ukraine killed 45 civilians, including six children – the deadliest attack on civilians since the spring. “Haven’t had time to recover from one tragedy, there is already another one,” said Kyrylo Tymoshenko, the deputy head of the Ukrainian presidential office. Separately, Ukraine reported intense fighting overnight in the east of the country, where both sides have taken huge losses for little gain in intense trench warfare over the last two months. Ukrainian forces repelled attacks in the eastern city of Bakhmut and the nearby village of Klishchiivka, the Ukrainian military said. Russia has focused on Bakhmut in recent weeks, claiming last week to have taken the mining town of Soledar on its northern outskirts. After big Ukrainian gains in the second half of 2022, the frontlines have hardened over the last two months. Kyiv says it hopes new western weapons will allow it to resume an offensive to recapture land – especially heavy tanks, which would give its troops mobility and protection to push through Russian lines. Western allies will gather at a US airbase in Germany on Friday to pledge more weapons for Ukraine. Attention is focused in particular on Germany, which has power of veto over any decision to send its Leopard tanks, which are fielded by armies across Europe and widely seen as the most suitable for Ukraine. Berlin says a decision on the tanks will be the first item on the agenda of Boris Pistorius, its new defence minister. Britain, which broke the western taboo by promising a squadron of its Challenger tanks, has called on Germany to approve the re-export of Leopards. Poland and Finland have said they would be ready to send Leopards to Ukraine if Berlin allows it.