Bodies covered with blankets lie in a field near the village of Blahodatne on Thursday after 11 Ukrainian troops were killed in an attack by pro-Russian activists. Ivan Sekretarev / AP

At least 11 Ukrainian troops were killed and about 30 others were wounded Thursday when pro-Russian armed men attacked a military checkpoint, the deadliest raid in weeks of fighting in eastern Ukraine. The attack comes three days before the country's presidential vote. The bodies of 11 troops were scattered around the checkpoint on the edge of the village of Blahodatne, about 20 miles south of the city of Donetsk, according to The Associated Press. Witnesses said the attack left more than 30 troops wounded, some in grave condition. Three charred Ukrainian armored infantry vehicles, their turrets blown away by powerful explosions, and several burned trucks were at the site. A military helicopter landed nearby, carrying officials who inspected the area.

Click for updates and analysis The Ukrainian Defense Ministry confirmed the attack but wouldn't comment on casualties. There was no report of casualties on the pro-Russian side. In the town of Horlivka, a rebel commander claimed responsibility for the raid and produced an array of weapons the rebels said they had seized. "We destroyed a checkpoint of the fascist Ukrainian army deployed on the land of the Donetsk Republic," said the commander, who wore a balaclava and identified himself by his nom de guerre "Bes," Russian for "demon." "The weapons you see here have been taken from the dead. They are trophies," he said, showing several dozen items, including automatic and sniper rifles, rocket grenade launchers and bulletproof vests carefully laid out in the courtyard in the Horlivka city police headquarters occupied by the rebels. "People living in western Ukraine: Think about where you are sending your brothers, fathers and sons, and why you need any of this," the commander said.

Scores have been killed in recent weeks in fighting in eastern Ukraine between pro-Russian rebels, who have seized government buildings, and government troops. Thursday's carnage cast a shadow over Ukraine's presidential vote, set for Sunday. Rebels in the east have pledged to derail the process. Authorities in Kiev see the vote as a chance to defuse tensions and stabilize the country, although they have admitted it will be impossible to carry out in some areas in the east, where election officials and voters have faced intimidation and threats. Many in the east resent the government in Kiev, which came to power after the ouster of pro-Russian President Viktor Yanukovych in February following mass protests. They believe Kiev is run by nationalists bent on repressing Russian speakers. But many local residents 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 that appeared to come from government positions badly damaged several houses Thursday. Zinaida Patskan, 80, had the roof of her house torn by an explosion, which also shattered one of the walls. "Why are they 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 the Ukrainian forces cease their offensive and withdraw from the region. Speakers at a rally also called for boycotting the presidential vote.

Troop withdrawal?