synchronization of the shelling with the negotiations was obvious. i think that, with this simple-minded method, russia is trying to pressure. do not lose time. we do not accept these tactics. >> meanwhile, europe's largest war in decades, fueling an exodus. the u.n. says more than half a million refugees have entered neighboring countries now. the train station here in lviv, where i am, has been packed for days. many of those fleeing -- women, children, also foreigners. ukrainian men between the ages of 18 and 60 -- those old enough to pick up a weapon -- are barred from leaving. cnn's matthew chance is on the ground near kyiv reporting from an area where a fierce battle between ukrainian forces and russian troops had just taken place. a warning -- some of the images in his report could be disturbing to some viewers.