DONETSK, Ukraine -- Sustained shelling in the main rebel stronghold in eastern Ukraine struck residential buildings and a hospital, killing at least four people and wounding 10 others, officials said, as government forces pressed forward in their campaign to rout the separatists.
Mortar fire struck the Vishnevskiy Hospital in Donetsk on Thursday morning, killing one and wounding five others, Donetsk city council spokesman Maxim Rovensky told The Associated Press.
"There was a sudden explosion," witness Dr. Anna Kravtsova said. "A mortar round flew through the window."
The shelling, which destroyed an array of equipment in the dentistry unit, also hit three nearby apartment buildings.
It followed a night of shelling in another neighborhood as the fighting between the government and pro-Russian separatists is inching ever closer to the city center. The mayor's office said in a statement posted on its website that three people had been killed, five wounded and several residential buildings destroyed during those attacks.
The government denies it uses artillery against residential areas, but that claim has come under substantial strain in the face of mounting evidence to the contrary.
Pro-Russian separatists in eastern Ukraine have been fighting the Kiev government since April. Ukraine and Western countries have accused Moscow of backing the mutiny with weapons and soldiers, a claim the Russian government has repeatedly denied.
The West has also accused Russia of most likely providing the insurgents with surface-to-air missiles that may have been used to shoot down a Malaysia Airlines passenger jet over rebel-held territory on July 17, killing all 298 people on board.
NATO Secretary General Anders Fogh Rasmussen, who met with leading officials in Ukraine on Thursday, said that the military alliance stood ready to support Ukraine with advisers and assistance.
While stopping short of committing to direct assistance in Ukraine's ongoing conflict, he said that NATO would intensify its cooperation with Ukraine on defense planning and reform.
Clashes erupted in central Kiev, the capital of Ukraine, as city authorities sought to clear away the remnants of a tent colony erected by demonstrators involved in the street uprising against pro-Russia President Viktor Yanukovych. At the time, protesters were angry about endemic corruption and wanted closer ties with the European Union.
In scenes reminiscent of that revolt, which climaxed with Yanukovych's ouster in February, demonstrators set alight tires in their face-off against a volunteer battalion overseeing the clean-up operation.
In eastern Ukraine, government troops have made tentative progress in their strategy to retake Donetsk and other towns and cities. Armed forces have refrained from pitched urban battles, and instead favored pushing back their opponents with artillery fire. It has led to a growing number of civilians casualties.
Vishnevskiy Hospital, one of the city's larger medical treatment facilities, is around 4 kilometers (less than 3 miles) from the main square. It has been used to provide treatment to civilian victims of the ongoing conflict.
"The hospital became a nightmare. This is absurd," said 37-year old patient Dmitry Kozhur. "We came here to keep living, but now we are risking death."
Kozhur said he now wants to join the 300,000 people that the mayor's office says have already abandoned the once 1 million-person strong city.
As AP reporters were leaving the hospital, they heard the sound of four rounds of artillery being fired from a nearby neighborhood under rebel control. Although it wasn't immediately possible to confirm the sequence of events, it appeared that the shells that hit the hospital may have been a response to rebel fire.
Neighbors of a house struck by rockets Wednesday said their homes were also near a position used by rebel artillery forces.
As the rebels struggle to push back Kiev's forces, fears of Russian intervention have grown. Western leaders have accused Russia of massing troops on the border with Ukraine and supplying rebels with weapons..
"We've noted with concern a new quality and quantity of arms and equipment flowing across the border from Russia into Ukraine, reports of shelling across the border as well as further attacks by illegal armed groups on targets in eastern Ukraine," said Sebastien Brabant, a spokesman for the EU's foreign policy chief.
Russia has always denied such claims.
Meanwhile, pro-Russian separatists in a breakaway region of Moldova have put their army on alert, claiming they fear military action from neighboring Ukraine and Moldova, a local news agency reported.
The Tiras news agency said that separatists in Trans-Dniester expected military activity starting from Aug. 26, the day before Moldova'sIndependence Day, but provided no details. Moldovan authorities accused separatists of trying to escalate tensions.
Trans-Dniester, a narrow strip of land squeezed between Ukraine and Moldova, is a tiny product of the fracturing of post-Soviet Europe. Russia stationed troops in Moldova in 1990, fearing that Moldova might try to reunite with Romania. The war that broke out in 1992, after Moldova declared its independence from the Soviet Union, left hundreds dead.
In eastern Ukraine, the military's strategy has focused on driving a wedge between Donetsk and the other main stronghold of Luhansk. Efforts to seal off the border with Russia have been thwarted as border troops come under sustained and heavy rocket fire. Ukraine says a lot of those attacks have been carried out by Russian troops, which Moscow also fervently denies.
In Kiev, demonstrators confronted city workers clearing a main square of long-standing barricades in a standoff that turned violent. A group of men set light to fuel-drenched tires and remonstrated with armed men from a pro-government battalion charged with protecting clean-up workers.
Dark plumes of acrid smoke from burning rubber rose above Independence Square as workers in high-visibility vests worked fast to dismantle barricades surrounding the main stage.
The square and surrounding streets were the site of huge winter protests that led to Yanukovych's ouster. Despite the election in May of a successor -- 48-year old billionaire confectionery tycoon Petro Poroshenko -- many said they would continue to squat on the square to ensure the new authorities lived up to their promise to usher in an era of transparent and accountable rule.
Many Kiev residents have fumed over the months-long sit-in, however, complaining that it severely disrupts traffic and blights the city's main thoroughfare.
City authorities have been negotiating with the protesters to clear the square since a new mayor was elected, but have met strong resistance from the several hundred demonstrators still camped out there.
While many barricades were removed Thursday, numerous tents remain in place.
-- Peter Leonard reported from Kiev. Juergen Baetz contributed to this report from Brussels.