The battle for Ukraine: Russian troops enter Kharkiv

A Russian Armoured personnel carrier (APC) burning during fight with the Ukrainian armed forces in Kharkiv

An Ukrainian Territorial Defence fighter examines a destroyed Russian infantry mobility vehicle GAZ Tigr after the fight in Kharkiv

A residential building damaged by recent shelling in Kharkiv.

Ukrainians line up to join the Territorial Defense Forces in Kharkiv. Russian troops have entered Ukraine's second city Kharkiv and fighting is under way, the head of the regional administration said.

Ukrainians are taken by truck to the front line to fight after joining the Territorial Defense Forces in Kharkiv, Ukraine.

A view of a residential building damaged by recent shelling in Kharkiv.

Refugees fleeing conflict in neighboring Ukraine arrive in Przemysl, Poland. Street fighting broke out in Ukraine's second-largest city Sunday and Russian troops put increasing pressure on strategic ports in the country's south following a wave of attacks on airfields and fuel facilities elsewhere that appeared to mark a new phase of Russia's invasion.

A Ukrainian soldier smokes a cigarette on his position at an armored vehicle outside Kharkiv, Ukraine

A destroyed armored personnel carrier (APC) on the roadside in Kharkiv, Ukraine

A Ukrainian fighter checks documents of people lined up to join the Territorial Defense Forces in Kharkiv, Ukraine

An unexploded Grad rocket is seen at a kindergarten playground in Kharkiv, Ukraine.

RFE/RL footage shows the tail section of a missile that hit a residential area of the city of Kharkiv.

Ukrainian soldiers walk past debris of a burning military truck, on a street in Kyiv, Ukraine. Russian troops stormed toward Ukraine's capital Saturday, and street fighting broke out as city officials urged residents to take shelter.

Members of civil defense prepare Molotov cocktails in a yard in Kyiv, Ukraine.

A deserted street is seen during a curfew after Russia launched a massive military operation against Ukraine, in Kyiv.

An empty street is seen due to curfew in the central of Kyiv, Ukraine.