After a firefight near the Russian border in the Ukrainian city of Kramatorsk -- pro-Russian militants seize the police headquarters.<br/> <br />Some 20 men, masked and carrying automatic weapons, shot at the building as they approached.<br/> <br />Some protested the takeover, calling for unity in Ukraine, but were quickly silenced by crowds of pro-Russia supporters.<br/> <br />This comes as Washington announced that U.S. Vice President Joe Biden will travel to Kiev on April 22.<br/> <br />Kiev said it would prepare troops to tackle what it calls an "act of aggression by Russia."
