A bomb blast at a rally in eastern Ukraine has killed two people on the first anniversary of the ouster of President Viktor Yanukovych, an event that helped trigger Russia's annexation of Crimea and a separatist uprising.

Ukraine's Interior Ministry described the blast at a pro-Kiev rally in Kharkiv as an act of terrorism and said it had been caused by a bomb. It said a police officer was among the dead and that about a dozen other people were wounded.

The Associated Press quotes a spokesman for the national security service as saying that four suspects were arrested in connection with the bombing.

The BBC says the rally in Kharkhiv was one of several being held to mark to mark the ouster of Moscow-leaning Yanukovych.

The AP writes:

"The violence in Kharkiv comes as Ukraine continues to be riven by tension and bloodshed stemming from Yanukovych's fall."A peace plan envisioning a cease-fire and pullback of heavy weapons was signed Feb. 12."Copyright 2016 NPR. To see more, visit http://www.npr.org/.