The Ukrainian city of Donetsk was rocked by blasts on Saturday, even as government forces and pro-Russia separatists agreed to create a buffer zone to separate the warring sides.
A memorandum signed early in the day called for the withdrawal of heavy weaponry and all foreign fighters from an 18 mile-wide buffer zone.
A Reuters correspondent in Donetsk, the main industrial hub in Ukraine's turbulent east, said several powerful explosions were heard in the morning. A plant producing munitions and industrial explosives had been hit, municipal authorities said.
Ivan Pirkhodko, a local official, said on Ukrainian television that an artillery shell striking the plant triggered the explosions, but it was not clear which side fired it.
Explosions were also heard from the direction of Donetsk Sergey Prokofiev International Airport, which government forces are still clinging on to despite rebels' attempts to loosen their control.
The deal reached in Minsk on Saturday by representatives of Ukraine, the rebels, Russia, and the Organization for Security and Cooperation in Europe (OSCE) marks an effort to add substance to a cease-fire agreement that was signed on Sept. 5 but has been frequently broken by clashes.
Ukrainian President Petro Poroshenko reluctantly agreed to the cease-fire, in a conflict that has killed more than 3,000 people, after forces suffered reverses on the battlefield that saw them lose a southern swathe of the Donetsk region along the border with Russia.
Kiev says Russian help involving more than 1,000 Russian troops proved the tipping point, though Moscow has denied any direct role in eastern Ukraine despite what Kiev and Western governments say is undeniable proof.
Former Ukrainian president Leonid Kuchma, representing Kiev at Saturday’s talks, said the two sides had agreed to move heavy artillery 9 miles away from the frontline on both sides to create an 18 mile-wide buffer zone. He also said that monitors from the OSCE would monitor the area to ensure compliance.
The deal also specifically banned flights by combat aircraft over the area of conflict and the establishment of new minefields.
"It should offer the population a chance to feel secure," said Igor Plotnitskyi, a rebel leader of the Luhansk region.
The pro-Russia rebels are primarily based near the cities of Donetsk and Luhansk in eastern Ukraine and the port city of Mariupol on the Sea Azov coast, but their positions elsewhere are not clear. Ukrainian government forces are operating from the airport in Donetsk, but the locations of their lines outside of the city are also unclear.
The newly signed memorandum also envisages the withdrawal of "all foreign armed units and weapons, as well as militants and mercenaries" — a diplomatic reference to Russian soldiers believed to be fighting alongside the rebels.
The Ukrainian crisis has pushed Russia-West relations to their lowest point since the Cold War. Faced with several rounds of Western sanctions that badly hurt the Russian economy, Russia's President Vladimir Putin has pushed for a peace deal that would ease Western pressure while protecting Moscow's interests in Ukraine.