(CNN) — Ukrainian Defense Minister Rustam Umarov ordered an investigation into an alleged Russian ballistic missile attack on a gathering of Ukrainian soldiers from the 128th Mountain Assault Brigade.

According to the Ukrainian Armed Forces, the attack occurred on November 3 in a village on the front line in the Zaporizhya region. The Russian Armed Forces fired an Iskander-M missile at troops from the 128th Separate Mountain Assault Brigade, killing several soldiers and wounding local residents, according to the Armed Forces.

“All the circumstances of what happened will be clarified,” Umarov said in a statement on Facebook on Sunday. “I have instructed the chief inspector of the Ministry of Defense to conduct a full investigation into the facts of this tragedy.”

He added: “We must do everything possible to protect our people and provide honest answers to the families and friends of fallen soldiers.”

The State Bureau of Investigation of Ukraine (DBR) has launched a criminal investigation into the events, according to a statement posted on its website.

DBR said 19 soldiers from the brigade were killed in the attack.

The Major General added, “A comprehensive investigation is currently underway into all the circumstances of the tragedy.”

Ukrainian National Broadcasting Corporation Sospilny said the attack occurred during an awards ceremony.

The Ukrainian authorities did not comment on the reason for the gathering of soldiers or the number of casualties.

Ukrainian parliamentarian Mykhailo Volynets said that 28 people were killed and 53 injured as a result of the missile attack. He did not provide further details about the number of civilians killed and the number of soldiers. CNN was unable to verify these numbers.

Thus, mourning was declared for three days in the Zakarpattia region, the headquarters of the brigade.

The 128th Mountain Assault Brigade did not issue any official statement about the attack.

The brigade is participating in the Ukrainian counteroffensive in the south and has been participating in combat operations in eastern Ukraine since 2014.