The death toll from Russian missile strikes on eastern Ukraine’s city of Sloviansk rose to 11 Saturday as rescue crews tried to reach people trapped in the rubble of an apartment building, Ukrainian authorities said.

Ukraine’s air force said the country would soon have weapons with which to try to prevent attacks like the one Friday. The delivery of the Patriot air defense system promised by the U.S. was expected in Ukraine sometime after Easter, Ukrainian air force spokesperson Yuriy Ihnat said.