A helicopter crashed into a kindergarten in an eastern suburb of the capital, Kyiv, killing 18 people, including the interior minister of Ukraine.
Three children were among the dead and 15 more are being treated in hospital.
Denys Monastyrsky, the minister, was one of eight people in the helicopter.
According to officials, both the state secretary and his first deputy minister perished when the helicopter crashed in the Brovary suburb.
In a Facebook post, national police chief Ihor Klymenko claimed that the helicopter belonged to the state emergency service of Ukraine.
Oleksiy Kuleba, who is in charge of the regional military administration in Kyiv, said that the tragedy in Brovary had injured 29 people and killed 18 of them.
Children and staff were evacuated from the building when a fire broke out close to the kindergarten following the crash. The helicopter’s wreckage could be seen outside a burning building.
At the time of the crash, it was pitch black and hazy, and the initial reports suggest that the helicopter struck the kindergarten before coming to a stop close to a residential building.
Along with Mr. Monastyrsky, two other high-ranking interior ministry officials were killed. Yuriy Lubkovich served as state secretary while Yevgeny Yenin served as first deputy minister.