KYIV, Nov 23 - A Russian attack using cluster munitions killed three people Thursday in a suburb of Ukraine’s southern city of Kherson, a Ukrainian official said, bringing the number of civilians to die in a day of war to at least six.

Five people were wounded in what Ukrainian Interior Minister Ihor Klymenko said was heavy afternoon shelling of Kherson’s Chornobayivka suburb, The Associated Press reported. More than 60 residential and infrastructure buildings were damaged in the daylight attack, he said.

Cluster munitions — a type of bomb that opens in the air and releases smaller “bomblets” across a wide area — are used by both Russia and Ukraine, which has received them as military aid from the United States. Critics say the weapons litter the ground and harm and kill many more civilians than combatants.

Kherson city is the capital of a region of the same name that is located on the Dnieper River near the mouth of the Black Sea and a key gateway to Crimea. Russia annexed the Crimean Peninsula from Ukraine in 2014 and uses it for logistics operations and rear supply depots during the current war.

Of military significance and lying on the war’s long front line, the Kherson region has been a stage for heavy fighting. Ukrainian troops last week reported gaining multiple bridgeheads on the Russian-held eastern side of the river.

Before the afternoon attack, Russian forces fired other parts of the province with eight nighttime artillery barrages, killing a 42-year-old man in his apartment building and wounding another man, the Ukrainian presidential office said.

Russian shelling also killed two people in the Donetsk region of eastern Ukraine, the office said.

A stepped-up Russian bombardment of civilian infrastructure has prompted Ukraine and its Western allies to beef up air defense systems. Officials fear the Kremlin’s forces will repeat their aerial attacks on the Ukrainian power grid this winter in an effort to break the country’s will.

The grid is already showing signs of strain. Ukrainian national electricity operator Ukrenergo reported an energy deficit Wednesday due to a steep rise in consumption caused by a drop in temperatures after a spell of mild weather, a company statement said.

Ukrenergo asked system operators in Romania, Slovakia and Poland to provide emergency assistance.

At a meeting Wednesday of some 50 countries supporting Ukraine’s war effort, U.S. Defense Secretary Lloyd Austin said they were placing extra emphasis on ground-based air defense, with Germany and France leading the European effort to furnish equipment.

President Volodymyr Zelenskyy said in a Telegram post that “Ukraine’s sky shield is getting more powerful literally every month.” (ap/ez)