A large-scale missile attack on the eastern Ukrainian town of Kramatorsk killed at least 15 people Tuesday, most of them civilians, and wounded many more, officials said.
"Several dozen missiles hit the airport and residential houses on the outskirts of Kramatorsk," Alexander Motuzyanyk, spokesman for the government's Anti-Terrorist Operation said by phone from Kramatorsk, where the unit has its headquarters.
He said it was the first attack on the town since Ukrainian troops reclaimed it from Russia-backed separatists in May.
Each side accused the other of launching an attack in an effort to influence talks that are scheduled to begin Wednesday in Minsk, Belarus, aimed at reaching a cease-fire agreement.
Motuzyanyk said the missiles were Russian, and appeared to have been fired by the separatists. "These are definitely missiles not used before in the conflict and something Ukraine never had in its arsenals," he said.
The separatists accused Ukrainian troops of firing them.
"We don't have missiles in stock that can fly that far," Eduard Basurin, chief political officer of the self-proclaimed Donetsk People's Republic armed forces, said in a phone interview. "I am sure it is a provocation the Ukraine military organized on the eve of the Minsk talks to demonstrate how bad and unpredictable we are."
The dead included eight civilians and four servicemen, Ukrainian government authorities said. The status of three of the dead was not clear. Sixty-three people, roughly half of them civilians, were reported wounded.
"They must have been targeting the headquarters of the operation against them," presidential aide Yuri Biryukov said in an interview. He speculated that it was a show of force by the pro-Russia separatists before the Minsk talks.
Presidents Petro Poroshenko of Ukraine and Vladimir Putin of Russia, as well as German Chancellor Angela Merkel and French President Francois Hollande, are expected to meet in Minsk in what some regard as a last-ditch attempt to stop the war.
According to Motuzaynyk, Ukrainian military intelligence reported that the missiles were fired from the town of Horlivka, held by the separatists, about 48 miles south of Kramatorsk. The first salvo of about 20 missiles hit the military airport, he added, while a second salvo of about the same number of missiles hit a residential area nearby.
"We are still examining the remains of the missiles but it is already clear that they are either Smerch or Tornado, both large-caliber, sophisticated Russian weapons, powerful enough to reach targets up to 90 miles," he said.
Marina Yurko, a 36-year-old housewife, was running through the deserted streets to pick up her 10-year-old daughter from school as ambulance sirens were wailing in the neighborhood, she recalled.
"The kids were safe but not at school," she said by phone. "The teachers hid them in the basement of a grocery store nearby. You should have seen their eyes. They were scared witless and in shock."
Donetsk regional governor Alexander Kikhtenko advised people in the surrounding area to try to stay indoors for the next few days
Russia's involvement in the conflict "was much too obvious," said Yuri Butusov, a top Ukrainian defense expert.
"It is an all-out war Russia is waging against Ukraine," Butusov said in an interview. "This is something the negotiating parties in Minsk should bear in mind full well."
Miles away from Kramatorsk, near the seaport of Mariupol, there were conflicting reports about who was in control of several towns in the surrounding Donetsk region.
The towns -- Pavlopol, Kominternovo, Berdyanskoye and Shirokino -- were seized by separatists in August. The Ukrainian military claimed to have taken them back on Tuesday.
"Very serious combat losses were inflicted on the enemy," said Alexander Turchinov, head of the National Security and Defense Council. Turchinov, who was in charge of the operation, was quoted in a statement posted on his agency's website.
The separatists denied the losses and said they had repelled the attack. Basurin said the Ukrainian military only entered the town of Shirokino "and put up their flag over one of the houses before they were kicked out by our troops."
Basurin also said the separatists had entrapped about 5,000 Ukrainian troops around the town of Debaltsevo.
Ukraine's Defense Ministry denied that claim, issuing a statement that said the situation around Debaltesevo, a strategic railway junction, was "complicated" but "under control."