Near the Ukrainian rebel stronghold of Slaviansk, residents gawk over a blast site.

They say government forces fired a shell in their village on Monday.

Payback from the government in Kiev, they say, for holding a referendum on independence ahead of national elections.

(SOUNDBITE) (Russian) VIKTOR, RESIDENT OF VILLAGE NEAR SLAVIANSK, SAYING:

"We had a referendum, we voted. Kiev does not recognize our vote, our opinion. So this is the way they try to persuade us."

Pro-Russian separatists in the east refuse to take part in Sunday's crucial all-Ukraine election.

In Kiev, the Interior Minister says a rapid-reaction force is in place to snuff out attempts to wreck the vote.

(SOUNDBITE) (Russian) ARSEN AVAKOV, INTERIOR MINISTER OF UKRAINE, SAYING:

"In hot spots, which we call red and pink zones, special procedures will be put in place with fast-response working groups created to fight provocation."

But the U.N. thinks dark shadows loom ov