An NBC journalist is reporting from the Ukrainian base under siege.

A public bus has shown up now with two vans. Troops are getting into vans in front with plain clothed men pic.twitter.com/ywKXe6Via2

— Ed Flanagan (@edmundflanagan) March 18, 2014

Retweet: From viewfinder of #nbcnews shooter @tony_day, Russian soldiers staging near #ukraine installation Entrance. pic.twitter.com/aqQkDs2Q0A

— Ed Flanagan (@edmundflanagan) March 18, 2014

Yellow bus has been pulled back. Armed men with 50 caliber sniper rifles seen taking positions around #Ukraine installation.

— Ed Flanagan (@edmundflanagan) March 18, 2014