Sporadic shelling and machine gunfire rang out early Sunday on the outskirts of a key Ukrainian city, straining a fragile ceasefire between the government and pro-Russian separatists.
While the source of the weapons fire near the strategic port city of Mariupol in southeastern Ukraine was not immediately clear, it followed other challenges to the fledgling truce, which took effect Friday.
Artillery and machine gunfire were heard late Saturday near Mariupol, where a gas station was ablaze and cars carried wounded civilians down the roads, CNN wrote.
The warring sides blamed each other for violating the ceasefire.
The Russian news agency Itar-Tass late Saturday quoted rebel officials as saying that Ukrainian forces continued to shell the flashpoint city of Donetsk and rebel positions near Mariupol. The RIA Novosti news agency reported that four Donetsk residents were killed in the shelling.
On the other hand, Ukrainian National Security and Defense Council spokesman Col. Andriy Lysenko told reporters in Kiev on Saturday that the situation was calmer than before the truce, but that there had been a number of "provocations" by rebels. They included 10 instances of shelling in the Donetsk and Luhansk regions, he said.
In a sign the government was still hoping to stick to the ceasefire deal, Lysenko said a prisoner exchange would begin soon, although he didn't specify a time or date.
'So much confusion'
Ukrainian forces and pro-Russian rebels have been locked in vicious fighting in eastern Ukraine since April, leaving more than 2,200 people dead, according to the United Nations.
The conflict has triggered a humanitarian crisis in the region, where shelling has destroyed homes and infrastructure. Nationwide, more than a million people have been displaced from their homes by the fighting, most of them in the east.
Ukrainian forces and the rebels have engaged in fierce fighting over the past week in the territory between the Russian border and Mariupol.
A previous unilateral ceasefire declared by the Ukrainian government in June broke down after 10 days.
Poroshenko and Putin talk
Ukrainian President Petro Poroshenko had a phone conversation with Russian President Vladimir Putin after the signing of the ceasefire deal in the Belarusian city of Minsk, Poroshenko's office said Saturday in a statement.
The leaders agreed that the ceasefire in eastern Ukraine has been mostly upheld and they discussed further steps to make the truce last, the statement said.
Some areas at the heart of the conflict reported that calm was prevailing.
Luhansk city council said that Saturday was the first day in over a month with no shooting. The city office has started working on repairs to the power and water supply.
Russian warning over sanctions
In spite of the ceasefire agreement, Putin remains under pressure from the West. The Ukrainian government and the West accuse Moscow of supporting the rebels with weapons and fighters -- allegations that Moscow has repeatedly denied.
Hours after the truce came into effect, EU leaders meeting in Brussels, Belgium, agreed on a new round of economic sanctions against Russian interests. They are due to be formally adopted on Monday.
Russia's Foreign Ministry warned Saturday that if new EU sanctions are imposed, Russia "certainly will respond," Russian state-run news agency Itar-Tass reported.
