Sept 1 (Reuters) - Explosions were heard in Ukrainian capital Kyiv early on Tuesday, a Reuters witness said, with local authorities saying on the Telegram messaging app that four people were injured and asking people to seek shelter.

Only shoot at Russian occupiers, president says, after three officers wounded in clash; Patriots could take years to make, says Rubio. What we know on day 1,653

US Secretary of State Marco Rubio has confirmed that Washington and Kyiv are negotiating a license that could allow Ukraine to produce missiles for the US-made Patriot air-defense system, reviving an idea that President Donald Trump appeared to downplay only weeks ago.

Parents and children in Ukraine and Russia gathered on Tuesday for a traditional 'Knowledge Day' celebrations, marking the fifth school year since Russia's invasion, but an air raid alert

Russian forces relentlessly battered Kyiv and cities in the region around the Ukrainian capital for a fifth straight day, leaving some supermarket shelves bare after repeated strikes on warehouses.

The nearly constant air raids, a shift from years of largely overnight attacks, have left residents exhausted and on edge.

Ukraine has urged the International Civil Aviation Organization (ICAO) to ask its members to fully ban operations in Russian airspace, a day after President