BLAHODATNE, UKRAINE (TIP): Three days before Ukraine holds a presidential vote, pro-Russia insurgents attacked a military checkpoint on Thursday in eastern Ukraine, killing at least 11 troops and wounding at least 33 others in the deadliest raid yet in weeks of fighting. A rebel group who claimed responsibility for the attack said one of their own was also killed.

AP journalists saw 11 dead Ukrainian soldiers scattered around a checkpoint near the village of Blahodatne, 30 kilometers (20 miles) south of the major city of Donetsk. Witnesses including a medical worker said 33 Ukrainian troops were wounded in the attack and that some of them were in grave condition. All the wounded were being treated at nearby medical facilities. The Ukrainian defense ministry confirmed the attack but wouldn’t comment on casualties. Ukraine’s acting Prime Minister Arseniy Yatsenyuk in televised comments blamed Russia for backing the rebels in the Donetsk and Luhansk regions, which have declared independence from the government in Kiev.

Thursday’s carnage cast a shadow over Ukraine’s upcoming presidential vote on Sunday, which separatists in the east have pledged to derail. Authorities in Kiev see the vote as a chance to defuse tensions and stabilize the country. Even so, they have admitted it will be impossible to stage the vote in some eastern areas where election officials and voters have faced intimidation and sometimes death threats from the rebels.

Three charred Ukrainian armored infantry vehicles, their turrets blown away, and several burned trucks were seen at the site in the Donetsk region. A military helicopter landed, carrying officials who inspected the area. Residents said attackers used an armored bank truck, which the unsuspecting Ukrainian soldiers waved through, and then mowed them down at point-blank range. Their account couldn’t be independently confirmed.

In the town of Horlivka, a masked rebel commander claimed responsibility for the raid and showed an array of seized Ukrainian weapons. “We destroyed a checkpoint of the fascist Ukrainian army deployed on the land the Donetsk Republic,” said the commander, who wore a balaclava and identified himself by his nom de guerre, “Bes,” Russian for “demon.” He said one of his men also was killed.

“The weapons you see here have been taken from the dead, they are trophies,” the rebel commander said, showing automatic and sniper rifles, rocket grenade launchers and bulletproof vests in the courtyard of the occupied Horlivka police headquarters. “People living in western Ukraine: Think about where you are sending your brothers, fathers and sons, and why you need any of this,” he added. Many in the east resent the government in Kiev, which came to power after a pro-Russian president fled in February following months of protests, seeing it as nationalists bent on repressing Russian-speakers.

But many locals also have grown increasingly exasperated with the rebels, whom they blame for putting civilians in the crossfire. In the village of Semenovka on the outskirts of Slovyansk, artillery shelling badly damaged several houses on Thursday. Zinaida Patskan, 80, had her roof torn away by an explosion that also shattered a wall. She said she was hiding under a kitchen table with her cat, Timofey, when the shelling came.

“Why they are hitting us?” she said, bursting into tears. “We are peaceful people!” About 100 Semenovka residents later vented their anger against the central government, demanding that Ukrainian forces cease their offensive against the separatists and withdraw from the region. Speakers at the rally also urged residents to boycott the presidential vote. While fighting raged in Ukraine, Russia’s Defense Ministry said Thursday its forces were leaving the regions near Ukraine as part of a massive military pullout ordered by President Vladimir Putin.

It said four trainloads of weapons and 15 Il-76 heavy-lift transport planes had already left the Belgorod, Bryansk and Rostov regions. Nato had estimated Russia has 40,000 troops along the border with Ukraine. Gen. Philip Breedlove, Nato’s supreme commander in Europe, told reporters in Brussels that some Russian military movements had been detected but it was too early to assess their size or importance. He said a very large and capable Russian force still remained close to Ukraine.