The minister, Denys Monastyrsky, was the highest-ranking government official to die since Russia’s invasion began in February last year. At least three children were also killed in the crash, which damaged a kindergarten and a 14-story residential building, according to the State Emergency Service. The crash occurred at 8:20 a.m., a time of day when parents typically drop their children off at the school.
The cause of the crash, which involved a State Emergency Service helicopter, was not immediately clear, but there was no initial information that the aircraft had been shot down.
Kyrylo Tymoshenko, the deputy head of the Ukrainian president’s office, said that the government officials onboard the helicopter had been traveling to one of the “hot spots” in Ukraine. The investigation into the cause of the crash would take some time and would include a team of specialists, he told reporters in a morning briefing at the scene.
He declined to provide further details on the potential cause of the crash and appealed to witnesses to contact the police.
Images posted from the scene showed smoke rising over a residential area in the suburb, Brovary, and a long trail of fire that could be where fuel was spilled. One photo appeared to show damage to the upper story of the kindergarten, and another showed the crumpled remains of the helicopter, some of the seats still visible.
A witness at the scene told Suspilne, Ukraine’s national public broadcaster, that she had seen the helicopter on fire and spinning in a circle before it hit the ground.
President Volodymyr Zelensky of Ukraine called the crash a “terrible tragedy.”
“The pain is unspeakable,” he said in a statement posted to his Telegram channel, adding that he had instructed the security services, the national police and other authorities “to find out all the circumstances of what happened.”
Ukraine’s Parliament said in a statement that those killed alongside Mr. Monastyrsky included Yevhen Yenin, the first deputy minister for internal affairs; and Yurii Lubkovich, the state secretary. Ihor Klymenko, the head of the national police service, said in a statement posted on his Facebook page that emergency responders were working at the scene.
In total, 18 people had been confirmed dead as of Wednesday morning, including the three children, according to statements from Ukrainian officials. Twenty-two people who were wounded were being treated in the hospital, including 10 children.
Mr. Tymoshenko said that of those killed, nine had been onboard the helicopter when it crashed. The rest of the dead were children, parents or others on the ground, he said.
As news of the officials’ deaths circulated, tributes began surfacing online.
“A loss for the family and Ukraine. A personal loss,” Ruslan Stefanchuk, the chairman of Ukraine’s Parliament, wrote of the death of Mr. Monastyrsky in a post on Twitter. He described him as a friend, adding: “It’s not fair. My sincere condolences to the family.”
Anton Gerashchenko, an adviser to Ukraine’s Ministry of Internal Affairs, said in a post on his Telegram account that “everyone who was on board the helicopter were patriots of Ukraine, everyone in his place defended and strengthened Ukraine.”
“The causes of the tragedy are being established by investigators,” he added. “We will soon find out whether it was sabotage, a technical malfunction or a violation of flight safety rules.”
Oleksandra Mykolyshyn contributed reporting.