Fifteen people, including eight children, were wounded in the accident at an unplanned exhibition of military equipment on Saturday in the northern Ukrainian city, local officials said. Four remained in the hospital on Sunday.

“Two people who were directly involved in the tragic incident in Chernihiv were detained on suspicion of committing a criminal offence,” Zelensky said in his nightly video address. “The State Bureau of Investigation is carrying out criminal proceedings.”

Viacheslav Chaus, the head of Chernihiv’s regional administration, earlier yesterday said on Ukraine television that the administration had not been informed of any military presence at the public event.

“If there had been a message that there would be soldiers, then we would have intervened in the situation and the military would not have taken part in such events,” Chaus said.