KYIV, Ukraine (AP) — A top aide to the commander of Ukraine’s military was killed by a grenade given to him as a birthday gift and not in a targeted attack, the interior minister said.

Maj. Hennadii Chastiakov died in the tragic accident Monday that badly injured his 13-year-old son, Interior Minister Ihor Klymenko said on Telegram.

A colleague presented six new grenades as a gift to Chastiakov, who was a top aide and close friend to Gen. Valerii Zaluzhnyi, for his 39th birthday, Klymenko said.

Chastiakov was showing off the grenades to his family at home when his son took one and began twisting the ring.

“The serviceman then took the grenade from the child and pulled the ring, leading to a tragic explosion,” Klymenko said.

Police are investigating the incident in the village of Chaiky in the Kyiv region.

The officer’s death was the second fatal tragedy in less than a week for Ukraine’s military.

A Ukrainian brigade holding a ceremony in Zaporizhzhia to honor troops on Friday was struck by a Russian missile that killed 19 soldiers, one of the deadliest single attacks reported by Ukrainian forces.

The commander of the 128th Separate Mountain Assault Brigade, Dmytro Lysiuk, was suspended as authorities investigate why the Rocket Forces and Artillery Day event was held near the front line, where Russian reconnaissance drones could easily spot the gathering.

Ukrainian media reported that Lysiuk was late for the ceremony and didn’t suffer injuries.

“It will be determined who specifically violated the rules regarding the safety of people in the area of the enemy’s aerial reconnaissance access,” President Volodymyr Zelenskyy said. “There will be no avoidance of responsibility.”

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