"We began to shoot back from behind the barricades and we threw Molotov cocktails at them," Zhadobin said. Two of the vehicles caught fire and the attackers fled in the other two, he said.
The Ukrainian Interior Ministry's office in the eastern Donetsk region said three people died in the attack and three others were wounded. The statement said some of the attackers were also killed or wounded, but the number wasn't known. Russian state television reported that two of the attackers were killed.
In Moscow, the Russian Foreign Ministry quickly blamed the clash on the Right Sector, a nationalist Ukrainian group that has supported the pro-Western interim government in Kiev, the capital.
But a spokesman for Right Sector, Artyom Skoropatskiy, denied any involvement in Sunday's shootout, which he called a provocation staged by Russian special services.
Ukraine's Security Service also called the attack a "cynical provocation" staged from "the outside."
Russian state and other Kremlin-friendly television channels showed pictures of items said to have been seized from the attackers and the two captured vehicles, which were pockmarked by bullets and gutted by fire. The items included weapons, ammunition, maps and the business card of Right Sector leader Dmytro Yarosh.
This gave rise to a flood of humorous posts on Ukrainian Twitter with the hashtag "VizitkaYarosha," or Yarosh's business card.
A man said to be a member of Right Sector and one of the attackers was later paraded before the television cameras in the custody of an insurgent wearing camouflage fatigues and a black balaclava. The man said he would advise other Right Sector activists against coming to eastern Ukraine.
"There is a war here," he said in footage broadcast by Russia's Channel One. "People here are defending their land, defending their home and their rights."