DONETSK, Ukraine -- After days of street battles and weeks of shelling, Ukrainian troops made a significant push Wednesday into rebel-held territory, claiming control over a large part of the separatist stronghold of Luhansk and nearly encircling Donetsk, the largest rebel-held city.
The advance of the Ukrainian army against pro-Russian separatists comes as the civilian death toll is mounting from sustained artillery strikes and rebel cities are slipping into a humanitarian disaster. At least 52 deaths were reported Wednesday, along with 64 wounded - and due to the dangers of the war zone in eastern Ukraine, no deaths were reported from Luhansk, meaning the actual toll could be even higher.
Ukrainian troops have been trying for weeks to drive the rebels out of Luhansk and cut off Donetsk, a city of 1 million that has shrunk by a third as frightened residents fled. In the last few days, several neighborhoods in Donetsk have been hit with sustained artillery fire and fighting on the city's outskirts has become more intense.
The death toll mounted quickly on Wednesday. In the Donetsk region, 43 locals were killed and 42 wounded in less than two days, including in two deadly artillery attacks Wednesday afternoon in the capital of Donetsk, local authorities said. In addition, nine troops died and 22 were wounded in fighting in a town outside Donetsk.
Luhansk city authorities reported running battles between the two sides. By early evening, government forces took control of "significant parts" of Luhansk, an eastern city just 12 miles from the Russian border, said Andriy Lysenko, a spokesman for Ukraine's National Security Council.
A Ukrainian SU-25 plane was also shot down near Luhansk, Lysenko told TV station 112 late Wednesday. He said the location of the pilot was still unknown.
Hard-hit Luhansk has been without electricity, running water or phone connections for 18 days due to the fighting. Russia has sent a massive aid convoy to help residents there but it is still stuck at the border, not yet approved by Kiev because its proposed route lies through rebel-held territory.
Ukraine has accused Russia of arming and supporting the separatists, a charge Russia denies. Ukraine and the West fear the massive aid convoy -- over 200 trucks -- will be used in some way to help the separatist militia.
In a sign that the impasse over the aid convoy could be nearing resolution, however, an official with the international Red Cross in Geneva told the Reuters news agency on Thursday that a team from the NGO had "visited Luhansk (on Wednesday) to check the roads and establish contacts for the delivery of the convoy, having received security guarantees for the mission."
ICRC spokesman Ewan Watson told Reuters "last-minute decisions from the Ukrainian side have delayed the process," but he was hopeful the convoy could roll onto Ukrainian soil "shortly."
Donetsk, meanwhile, has come under daily shelling attacks from all sides. On Wednesday morning, rockets slammed into residential areas, including the Donetsk suburb of Makiivka. More rockets hit in the afternoon.
"I was with my grandmother in the bathroom, because there is a bearing wall in there," said Anna Zyukova, 22. "And then all of sudden, bam-bam."
Many Donetsk residents have been taking refuge in improvised bomb shelters in the basements of apartment building. Residents in Makiivka huddled in groups near one such shelter Wednesday, chatting and listening as rockets flew in and out several miles away.
At a rebel camp closer to the fighting, a rebel commander who identified himself only as "Chaika" -- Russian for seagull -- said he was at a loss to explain why army shells were hitting apartments.
"We purposely don't take up positions where people live," he said -- a claim that Ukrainian officials have repeatedly dismissed.
An Associated Press reporter saw the aftermath of one artillery attack in central Donetsk on Wednesday evening. Windows were blown out in several apartment blocks, and the shells left craters on the ground.
The Donetsk mayor's office reported that nine people died and 13 were wounded in artillery attacks in two neighborhoods earlier in the day.
As the government sought to retake a major railroad and a highway that leads to Russia, nine troops were killed and 22 wounded overnight in Ilovaysk, a town east of Donetsk, said Lysenko, the government spokesman. Fighting continued there Wednesday even though government forces had gained control of the town, he said.
Among those killed in Ilovaysk was a Ukrainian-American known by the nom de guerre of "Franko," said Anton Herashchenko, an adviser to the interior minister. He said Franko was an American citizen with a military background who had been living in eastern Ukraine for 10 years and who had obtained Ukrainian citizenship before joining the army.
The Kiev government is also pursuing diplomatic efforts to resolve the conflict, which the United Nations says has killed more than 2,000 people and displaced over 340,000. The fighting began in mid-April, a month after Russia annexed Ukraine's Black Sea peninsula of Crimea.
Ukrainian President Petro Poroshenko will host German Chancellor Angela Merkel this weekend in Kiev before meeting next week with Russian President Vladimir Putin in Minsk, the capital of Belarus.
Reuters quoted the speaker of Russia's parliament as saying Thursday that the meeting in Minsk would be "one of the stages on the way toward de-escalation of this conflict."
In Moscow on Wednesday, protesters scaled one of the city's famed Stalin-era skyscrapers and painted the Soviet star on its spire in the national colors of Ukraine. They also attached a blue-and-yellow Ukrainian flag to the top of the 580-foot building.
While Moscow police detained four suspects and charged them with vandalism, a crime punishable with up to three years in prison, Poroshenko welcomed the flag-hoisting over the skyscraper in a video message, calling it a "symbolic" gesture.
He then urged Ukrainians all over the world to fly Ukrainian flags at their homes in celebration of the country's Independence Day holiday on Sunday.