Ukrainian forces not far from Slaviansk, where a ceasefire appears to be over.

This wasn't the only exchange of gunfire over the weekend.

Three Ukrainian soldiers were killed on Saturday after pro-Russian rebels attacked their outpost.

It isn't clear whether the burnt down post on the right with the flags is the same one.

In Kiev, thousands gather to say the ceasefire isn't working.

(SOUNDBITE) (Russian) PROTESTER VOLODYMYR, SAYING:

"The president announced a truce a week ago. Twenty people died within that time. Then he extended it by three more days. Our young boys who were under 25 years old were killed yesterday. Four were killed the day before yesterday. How long can this last? Who is there to negotiate with? Who? The representatives of Moscow?"

One sign reads, "The only language terrorists understand is the language of force."

Others have called for martial law.

The ceasefire, which was extended on Friday, ends Monday night.