An explosion occurred again in Sumy after a warning of a ballistic missile threat, UNN reports .
The sound of an explosion is heard in Sumy, Suspilne correspondents report.
An air alert has been declared in Sumy region, Kyiv and a number of other regions due to the threat of ballistic weapons.
"The air alert is related to the threat of ballistic weapons! Stay in shelters!" the KCSA said in a statement.
Earlier, the Air Force warned of the threat of ballistic missile attacks from the northeast.