A Russian strike on a correctional facility in southern Ukraine killed at least 16 people and injured dozens more just before midnight on Monday, Ukrainian officials said. It appeared to be the deadliest attack on a Ukrainian prison since Russia launched its full-scale invasion more than three years ago.

The attack was part of a wave of strikes directed at 73 Ukrainian cities and villages over Monday night and Tuesday morning, President Volodymyr Zelensky of Ukraine said in a statement. It came only hours after President Trump renewed his call for the Kremlin to end the bloodshed.

On Monday, Mr. Trump expressed frustration with Russia’s persistent targeting of civilians and the staggering battlefield losses on both sides.

He said he would give President Vladimir V. Putin 10 to 12 days to show a serious commitment to a cease-fire before imposing broad sanctions, including measures that would limit the Kremlin’s ability to finance its war through oil exports.

Previously, Mr. Trump gave Moscow 50 days to change course.

Officials in Moscow largely waved off the threat, and the Russian military showed no signs of slowing its offensive campaign on the front or its increasingly deadly daily bombardments.

Around the same time the prison was attacked, a ballistic missile struck a hospital complex and maternity ward in the Dnipro region, Ukrainian officials said.