The Kiev government said Wednesday that 300 pro-Russia militants have been killed in the past 24 hours in bloody clashes with Ukrainian forces in the town of Slavyansk.

Fighting raged on for the second day between Ukrainian government forces and pro-Russia rebels in Slavyansk, forcing many residents to flee the eastern town.

Many pro-Russia rebels were killed in what the Ukraine government is calling an "anti-terrorist operation" to snuff out the rebellion, Reuters reports.

Rebels denied the number of losses, saying less people were killed in the clashes than have been reported.

Families were forced to escape the inundation of artillery and gunfire, taking only as much as they could carry.

"We took only what was most necessary. We are going. We don't even know where," Andrei Bander, who has a 4-year-old daughter, told Reuters. "We will head to Russia though because it's clear we need to leave Ukraine. I don't see anything good left here."

Water was shut off in Slavyansk Tuesday afternoon, and roads were blocked by Ukrainian forces, making it difficult for families to leave the town.

A spokesman for the government said that two military men had been killed, and 45 were wounded in the offensive, which was launched by government forces.

Rebels continued to deny the army's death toll of the rebels, and claimed that they shot down a military helicopter.

"Reports of 300 dead are not true. Losses to the Ukrainian side were more than ours," said Aleksander Boroday, "prime minister" of the self-proclaimed Donetsk People's Republic, as quoted by Interfax news agency.

Boroday said at a news conference later that separatists would train volunteers to fight in Donetsk as well.

"We have information that a storming of the city of Donetsk is being prepared by enemy forces and we are being forced to take measures such as mobilisation of volunteers," he said.

President-elect Petro Poroshenko, who was elected May 25 in a nationwide presidential election, ordered the offensive of government forces to halt the rebellion in the east.

Poroshenko, who supports the West, told President Obama Wednesday in Warsaw that he wants to implement a plan for a "peaceful resolution" after his inauguration, which is scheduled for Saturday.

Since fighting resumed, Kiev insists that the rebellion is being supported by Moscow, and accuses Russia of sending in volunteers to fight with the pro-Russia separatists. Moscow denies any direct involvement, and once again called for Ukraine to end its military offensive against the rebels and have open negotiations.

Government forces failed to stop the separatist rebellion in April, losing military equipment and undergoing many defections.

The army attack in Slavyansk followed a clash Monday with rebels in Luhansk, a town further east near the Russian border. Ukrainian army personnel said Wednesday that a border guard camp in Luhansk was evacuated after being attacked by rebels Monday. The rebels said the border guards surrendered.

British Prime Minister David Cameron also called on Russian President Vladimir Putin to engage with Ukraine President-elect Petro Poroshenko while at the G7 Summit in Brussels Wednesday.

G7 released a statement condemning Russia's annexation of Crimea, The Guardian reports.

"We are united in condemning the Russian Federation's continuing violation of the sovereignty and territorial integrity of Ukraine," the statement said. The statement also condemned "the use of energy supplies as a means of political coercion" and called for energy security and the diversification of supplies to be "at the centre of our collective agenda."

Putin will meet with Cameron Friday, in addition to German chancellor Angela Markel and President Obama for the commemoration of D-Day in Normandy.

Putin is facing a possible long-term exclusion from the G7 due to his country's actions in Ukraine, which has prompted the U.S. to impose strict sanctions on the country.

According to The Guardian, Russia has removed 40,000 troops from the Ukraine border, but there are no signs that the country has stopped supporting the pro-Russia separatists in the east.