The fragile, 10-day cease-fire in eastern Ukraine expired Monday night with no immediate word from the country's president on whether he would extend it, and no sign that the pro-Moscow separatists had met his demands to ease the violence.
As the truce entered its final hours, Ukrainian President Petro Poroshenko discussed the situation in a phone call with the leaders of Russia, Germany and France, saying the rebels had not "fulfilled the conditions."
Among other things, he demanded that the rebels hand back border posts and allow international observers to monitor the cease-fire.
The phone call included Russian President Vladimir Putin, Germany's Chancellor Angela Merkel and France's Francois Hollande.
Poroshenko had already extended the cease-fire from seven days as part of a plan to end the fighting that has killed more than 400 people since April. The truce has been violated repeatedly, with the two sides blaming each other.
European leaders and the US have urged Russia to use its influence with the rebels to ease the bloodshed and have threatened to impose another round of economic sanctions against Moscow.
While Putin has expressed support for the cease-fire, the West has accused Russia of allowing weapons and fighters to flow across the border into Ukraine.
White House spokesman Josh Earnest said that the US welcomes Putin's encouraging words but that the Russian leader must take "tangible actions" if he hopes to avoid further sanctions.
"We are still in a situation where those actions do not indicate a seriousness of purpose when it comes to de-escalating the situation in Ukraine," Earnest said.
French officials said Monday's phone call touched on establishing a full cease-fire by both sides, having international monitors on the border between Russia and Ukraine, freeing prisoners and holding substantial talks with the rebels.
Rebel leader Alexander Borodai on Friday welcomed having observers monitor the situation but rejected the demand to hand back the checkpoints.
Sporadic fighting flared early Monday despite the cease-fire. Shelling killed at least two people and ruined several apartments in the rebel-held city of Slovyansk.
One woman, 62-year-old Vera Sayenko, died when a shell hit her ninth-floor apartment, neighbors said.
"Everything we have collected in our life is destroyed. We have become poor," said Valery, whose apartment was also destroyed. He would not give his last name. "Show all Ukrainians what happened here. What else do they want, to ruin the town and kill people?"
Authorities were also investigating the death of a Russian cameraman working for Russia's Channel One.
Anatoly Klyan, 68, was fatally wounded Sunday when a bus carrying journalists and soldiers' mothers was hit by gunfire as it approached a military base in eastern Ukraine after dark.
Klyan was the fifth journalist to die since the pro-Moscow uprisings began in the wake of Russia's lightning annexation of the Crimea in March.
Poroshenko says the cease-fire is a first step toward peace. Further steps would include changes in the constitution to decentralize power and give more authority to Ukraine's regions.
The weapons that separatists used to shoot down Ukrainian aircraft, including the June 14 downing of a transport plane that killed all 49 aboard, were probably supplied by Russia, the US commander of NATO forces in Europe said Monday.
Air Force Gen. Philip M. Breedlove said at the Pentagon that the Russians are providing a variety of heavy weaponry to the separatists, including anti-aircraft weapons and tanks.