A Russian missile attack blasted homes in the southern Ukrainian city of Odesa on Friday, followed by a second missile that targeted first responders who arrived at the scene, officials said. At least 20 people were killed.

The attack occurred as Russians began voting in a presidential election that is all but certain to extend Vladimir Putin's rule by another six years after he crushed dissent, and as the war in Ukraine stretches into its third year.

The dead included a paramedic and an emergency service worker. At least 53 other people were wounded, officials said.

At least 10 houses in Odesa and some emergency service equipment were damaged in the strike, which started a blaze, according to emergency officials and regional governor Oleh Kiper.

The tactic of firing a second missile at the same location, aiming to hit rescuers, is known in military terms as a double tap. Such strikes often hit civilians.

Kiper announced that a day of mourning in Odesa would be held on Saturday — the second such observance in less than two weeks.

On March 2, a Russian drone struck a multistory building, killing 12 people, including five children.