Reports of casualties among government and separatist fighters have continued unabated since a cease-fire agreement was reached in February, but deaths among noncombatants had almost ceased.
That trend has been disrupted in recent days in an indication that the warring sides are again increasingly resorting to indiscriminate shelling.
The head of the government-controlled part of Luhansk region, Hennadiy Moskal, said in a statement on his official website that an elderly couple died when their car was struck by mortar fire Wednesday morning.
The statement said the strike occurred 20 kilometers (12 miles) into government-held territory.
Russia's Interfax news agency cited a rebel representative as saying that one resident in the town of Yenakieve was killed near a waste treatment plant during a 20-minute barrage.
The war has killed more than 6,400 people since April 2014.
As Ukraine's conflict shows little sign of abating, talks on implementing a shaky February cease-fire agreement have foundered.
Negotiators from the warring sides met in Belarus on Tuesday, but the session concluded without obvious progress.
The armistice requires both sides to pull back heavy weapons from the 450-kilometer front line, but international monitors tasked with vetting that process regularly note violations across the board.
Fighting is reported daily from multiple locations along the front.
Some of the most sustained unrest appears to be centered on the fringes of the main rebel stronghold of Donetsk.
Ukrainian member of parliament Yevhen Deydey, who acts as a liaison official for the government's Kiev-1 battalion, said Wednesday that rebels are focusing their shelling on two western Donetsk suburbs still in government hands.
"Krasnohorivka and Marinka are in flames. There is close-contact fighting taking place across the entire front. Militants are trying to break through," Deydey said in a statement.
Other military officials have confirmed the intensification in fighting in Marinka.
The Organization for Security and Cooperation in Europe said in its most recent status report, covering events on Monday, that its monitors heard 109 mainly outgoing explosions from the area around Donetsk airport, which is under rebel control.
That neighborhood is around 15 kilometers (9 miles) from Krasnohorivka and Marinka.