Seven ambulances were seen driving towards the facility, according to Reuters, and a further 19 ambulances were seen driving away from the base.
A Russian missile attack on a large Ukrainian military facility near the border with NATO member Poland on Sunday killed 35 people and wounded 134, a Ukrainian official said.
Russia fired more than 30 rockets at the International Peacekeeping and Security Center (IPSC), also called the Yavoriv Military Range, Lviv regional governor Maksym Kozytsky said.
It is located in Yavoriv, in the Lviv region, about 15 miles from Poland — a NATO and European Union member nation. Houses on the Polish side of the border shook when the salvo hit.
Russia’s defence ministry said the air strike destroyed a large amount of weapons supplied by foreign nations that were being stored at the facility, and that it had killed “up to 180 foreign mercenaries”.
The 360 square km (140 square miles) Yavoriv military facility, also known as the International Peacekeeping and Security Center, has long been used to train Ukrainian military personnel, often with instructors from the United States and other NATO countries.
At least 35 people were killed according to the regional governor, Aljazeera reports.
Seven ambulances were seen driving towards the facility, according to Reuters, and a further 19 ambulances were seen driving away from the base.
According to the US Army, the Yavoriv Combat Training Center was modeled after NATO standard combat training centers.
Foreign troops, including Americans, had participated in training at the base as recently as February.
Ukraine's defense minister Oleksii Reznikov described the targeting of the base as a "terrorist attack."
The attack near the Polish border came after Russia on Saturday warned the US that "pumping Ukraine with weapons from a number of countries orchestrated by them is not just a dangerous move, but these are actions that turn the corresponding convoys into legitimate targets."