Foreign military instructors worked at the Yavoriv military facility near the Polish border, which was hit by a Russian air strike on Sunday, according to Ukrainian Defense Minister Oleksii Reznikov, though it was unclear whether any were present at the time.

A ministry representative told Reuters that the ministry was still investigating whether any of the instructors were present at the time of the attack.

“Russia has launched an attack on the International Center for Peacekeeping and Security, which is located near Lviv. Foreign instructors are employed here. The victims’ identities are being clarified “Reznikov stated this in an online post.