A number of amateur videos posted online appear to show the helicopters being attacked. One video, later shared by the pro-Kiev Euromaidan PR account and picked up by the United Kingdom's Channel 4, appears to show a helicopter going down after being shot. The video has been independently verified by Storyful.
Other footage, which appears to have been shot and uploaded to YouTube by a pro-Russian activist, seems to show a helicopter being shot at over a militia checkpoint outside Sloyvansk.
And one more amateur video appears to show a crowd cheering in Russian as they see a large explosion in the distance, which the person who uploaded the video says is a Ukrainian helicopter crashing.
While it is difficult to conclusively confirm the authenticity of these videos, a representative of Euromaidan PR said they believed all three were authentic. They are just a handful of the many more that have been uploaded to YouTube over the past 12 hours.
The downing of multiple helicopters is being taken as proof that the pro-Russian militias are at least being armed by Russia. The Ukrainian Security Service is saying that at least one helicopter was shot down by a surface-to-air missile, which led Sweden's Foreign Minister Carl Bildt to tweet:
Ukrainian helicopters shoot down in Slovyansk. Some elderly ladies bought some RPG’s or missiles at the local grocery store, I assume.— Carl Bildt (@carlbildt) May 2, 2014