A third person has died as a result of a bombing in the eastern Ukrainian city of Kharkiv.
The Kharkiv city council's press service said on February 23 that a 15-year-old boy has also died from the injuries he received in the blast.
Two people, a policeman and an activist, were killed by the bombing on February 22.
A minute of silence was observed in Kharkiv on February 23 in honor of those who died and at least 10 others who were wounded in the explosion.
The bomb exploded during a march in Kharkiv marking the Maidan antigovernment protests in Kyiv one year ago that ousted President Viktor Yanukovych.
Those events in Kyiv helped spark the conflict that is currently raging in eastern Ukraine.
WATCH: Deadly Bombing Hits Kharkiv March
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Deadly Bombing Hits Peace March In Kharkiv
Meanwhile, parliament member Dmytro Tymchuk said Russian-backed separatist forces are concentrating near the southern Ukrainian port city of Mariupol.
Tymchuk posted a message on his Facebook page on February 23 saying that some 350 additional rebel fighters and about 20 armored vehicles -- including six tanks -- had arrived since February 22 to reinforce separatist units in the nearby Bezimenne district.
Tymchuk also said that some of the separatists who took part in the siege of the city of Debaltseve have returned to their stronghold in Donetsk.
Separatist forces took Debaltseve from Ukrainian government forces after days of intense fighting and artillery barrages, the final stages of which happened despite a cease-fire agreement brokered by the leaders of France, Germany, Russia, and Ukraine earlier in the month that was supposed to come into effect on February 15.
The separatists claimed the cease-fire deal did not apply to Debaltseve, which the rebels said was part of their territory in eastern Ukraine.
Ukrainian forces withdrew from Debaltseve on February 18.
The UNIAN news agency reported on February 23 that the head of the People's Remembrance Union, Yaroslav Zhilkin, said his group of activists had retrieved the bodies of 159 Ukrainian servicemen from Debaltseve since fighting calmed there.
Elsewhere in eastern Ukraine there was little sign of a full cease-fire.
The Ukrainian military says it will not start withdrawing heavy weapons from the front line in the conflict with separatists because the rebels have not completely ceased fire.
Under the terms of the cease-fire, both sides should pull their heavy weapons back 70 kilometers from the front line.
Ukrainian military spokesman Anatoly Stelmakh said on February 23 that while hostilities have lessened in recent days after separatist forces took the strategic town of Debaltseve, rebels shelled government troops twice overnight.
Another spokesman, Vladyslav Seleznyov, said in a televised briefing that because "the positions of Ukrainian servicemen continue to be shelled, there cannot yet be any talk of pulling back weapons."
Stelmakh said Ukraine would begin the withdrawal when "the enemy stops firing on our positions."
Ukrainian Colonel Valentyn Fedichev, deputy commander of the military operation against the separatists, said there had been 27 attacks against Ukrainian forces in the past day, which he said was less than in previous days.
Fedichev said "if the enemies continue to use their own heavy weapons, it is clear that Ukraine will continue to counteract these operations."
The Organization for Security and Cooperation in Europe's (OSCE) observer mission in Ukraine is responsible for monitoring any withdrawal of heavy weapons
OSCE spokesman Michael Bocuirkiw told the AP news agency on February 23 that monitors had seen heavy weapons movements by both sides but did not know if they were being withdrawn or redeployed.